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Sea balls

From Wikipedia, the free encyclopedia

Sphere of seaweed on a beach with others in the background
A Neptune ball on a sandy beach.

Sea balls are a group of aquatic phenomena. Real sea balls are spherical algae growth; non-real sea balls form through the movement of debris by water. The most well-known example of non-real sea balls, found on coasts of the Mediterranean Sea, are formed from decayed leaf fibres of the seagrass species Posidonia oceanica, though other variants worldwide are made of different organic materials; Mediterranean sea balls are typically referred to as Neptune balls.

Neptune balls have been used for millennia, such as for making shoes, ancient medicine, or to caulk ships, though their formation process has only become clear in recent years. Potential modern applications make use of the properties of Neptune balls which are rare in nature; for example, Neptune balls have been shown to be a good soundproofing material. Neptune balls would also be a more environmentally-friendly substitute for some synthetic materials.

In recent years, plastic waste, especially microplastics, has been interfering in the process of Neptune ball formation; studies and people have found plastic in many Neptune balls in the Mediterranean. Consequently, Neptune balls have been suggested as an indicator of plastic pollution in the sea, with concludingly positive first results.

Description

[edit]

Names and definitions

[edit]

Sea balls formed in the Mediterranean Sea have a variety of names. The name aegagropilae comes from the Greek αίγαγροσ (wild goat) and πῖλος (fur).[1] They are also known as aegagropiles, Neptune balls,[2][3] egagropiles,[4] egagropili,[5] Posidonia oceanica spheroids,[6] pilae stagnales, pilae marinae, pili marinae, sphaerae marinae, globuli marinae, and sphaerae thalassiae.[7] Historically, they have been known as okr elbahr and annabdti.[7][8] Neptune balls are known as pelotes marines or pelotes-de-mer in French,[7][9][a] Zeeballen in Dutch, motolini in Italian, and Seebälle in German.[7][b]

Historically, the term sea balls[c] has been used synonymously with Neptune balls and its alternative names.[12] More recently, sea balls has been used to describe Neptune balls,[5] other marine material spheroids,[13] and even fossils of sea balls.[8] According to German phycologist and botanist Bruno Schröder [de], there are two types of sea balls: non-real,[d] which means sea balls formed by wave action made of discarded plant matter and encompasses Neptune balls, and real,[e] which means sea balls that form through spherical plant growth.[7] Schröder wrote that the genus of algae Aegagropila is an example of plants that form real sea balls.[7] Canadian botanist W. F. Ganong also separated algal sea balls from sea balls formed by waves.[14]

Formation

[edit]
A sea floor with seagrass
Posidonia oceanica growing on the sea floor.

Posidonia oceanica is a seagrass species endemic to the Mediterranean Sea, whose remains form the Neptune balls found there.[1] In autumn, Posidonia oceanica loses its leaves.[15] The leaf sheaths remain attached to the rhizome when leaves shed, and are slowly buried by sedimentation in the "matte", an accumulation of dead rhizomes and roots.[15][16] During the burial process, leaf sheaths, which are rich in lignin, are eroded, releasing constituent fibres.[2][15] The sea rolls the fibres into a spherical shape, creating Neptune balls.[1][f] Then, ocean currents can dislodge Neptune balls from the sea floor; some drift into deeper waters and some are washed ashore.[2][15] Though details on where they travel during their relocation are not known, Neptune balls wash up on beaches especially frequently during storms.[3]

Appearance, properties, and applications

[edit]

Dry Neptune balls are light brown.[7] Neptune balls usually have a radius less than 8cm long; a study found that the mean radius is between 1.14cm and 2.68cm.[1][g] The study also found that the average mass of Neptune balls is 0.212g.[1][h] Another study described Neptune balls as having "diameter values from millimeters to centimeters up to 20 cm".[5] Neptune balls can be spherical, ellipsoidal,[17] or in-between.[7]

Their fibres are "relatively smooth", except for places in which salt crystals form following sea water evaporation.[1] Fibres on the outside of Neptune balls are often "broken into a disordered bundle of smaller fibers" because of the transport to the shore; however, this is unlikely to impact the formation process.[1] Leaf sheath cells in Posidonia oceanica have thin and lignified walls, so fibres provide the needed stiffness to form Neptune balls;[15] they are composed of 32% lignin, whereas Posidonia oceanica has 19% lignin.[17] The stiffness also comes from the density of Neptune balls.[1]

Neptune balls have been suggested as a soundproofing material, as they have similar absorption to that of mineral wool and polyester fibre.[18] Extracted lignin from Neptune balls has been suggested as a material for reinforcement.[17] The poor flammability and good thermal insulation of Neptune balls make them excellent for building insulation;[5][19] consequently, they have been sold as a building insulation material.[1] Neptune balls would have less of an environmental impact because Posidonia oceanica absorbs carbon dioxide,[18] and they would replace plastic fibres, which are unsustainable as they require oil extraction.[17] This would also reduce energy use and organic waste.[17] Procuring Neptune balls for insulation uses up to thirty times less energy than procuring mineral wool, rock wool, or petroleum-based foams.[19] However, Anna Sanchez-Vidal of the University of Barcelona argues against removing Neptune balls from beaches as they are part of beach ecosystems.[2] They bring humidity to beaches,[2] protect beaches against erosion, provide nutrients for dune plants, and feed beach arthropod communities.[15]

Distribution

[edit]

In the Mediterranean Sea

[edit]

Neptune balls formed from Posidonia oceanica can only be found on coasts of the Mediterranean Sea as Posidonia oceanica is endemic to there.[1] Posidonia oceanica Neptune balls have been found on the coasts of Spain, Algeria, Tunisia, and Turkey.[17] It is estimated that between 13 and 50% of initial Posidonia oceanica may have been lost since 1960,[15] reducing Neptune ball numbers. WWF estimated that 34% of Posidonia oceanica meadows have been lost in the past 50 years.[20] One cause is that seagrasses like Posidonia oceanica are at risk from heatwaves and industrial pollution.[2]

Worldwide

[edit]

On the east coast of Africa and on the coast of Australia, non-real sea balls made of Posidonia australis have been found.[7] Posidonia australis is also in decline.[2] Non-real sea balls made of marram grass have been reported at Dingle Bay, Ireland, in 1996 and 2006.[13] These varied in shape; some were spherical and had a diameter 7cm, whereas others were elliptical and over 25cm long.[13] Non-real sea balls made of fragments of marsh plant stems, rhizomes, and roots have been reported in Florida, United States.[21] Non-real sea balls have also been found in lakes and on the coast of Nova Scotia, Canada, the coast of New England, United States,[11] as well as on coasts of the North Sea.[7] Canadian botanist W. F. Ganong speculated that non-real sea balls occur "all over the globe".[11]

History

[edit]

The earliest known use of Neptune balls was in ancient Egypt, where they were used to make footwear.[22] The earliest known dated description of Neptune balls was in 1216 in Andalusia, Spain, where they were known as annabdti. Abul Abbas, a Moorish scholar, mentioned them in his book of travel, Kitab ar-rihlat, for supposedly having medicinal properties.[7][8] An Arabic pharmacologist, Ibu el Baither, called Neptune balls okr elbahr in his book Kitab al-Dschamie al-Kabir, noting supposed medicinal properties in dentistry.[7][8] Venetians used dry Posidonia oceanica leaves to pack glass, ceramics, and fish.[22] The Encyclopédie, published between 1751 and 1772, defined Neptune balls as "a substance usually an oblong, rounded or spherical ball shape, [and] fist-sized".[12] The Encyclopédie described that Neptune balls are formed from fibrous plant substances.[12] Henry David Thoreau mentioned aquatic spheroids in his 1854 book Walden.[14] Botanists in France have known that Neptune balls are formed from Posidonia oceanica remains since at least 1872, though theories that they are formed from the remains of pine cones existed in the 19th century.[11] In 1877, Hugh Algernon Weddell reported that Neptune balls found on beaches around Hyères are made of Posidonia caulini,[10][11] another name for Posidonia oceanica.[23] He disproved the theory that Neptune balls are made of algae; thus they were removed from the algae genus Aegagropila.[11] In 1897, Génau de Lamarlière stated that Neptune balls found on the coast of Spain are made of Posidonia oceanica, though other variants can be made of algae or pine needles.[24]

Plastic waste and climate

[edit]

A 2018–2019 study published in Scientific Reports investigated the role of Neptune balls in trapping and extracting plastic debris from sea and carrying them to shore,[2][15] which has been described as "mopping up ocean plastic from the seafloor".[2] The study examined the accumulation of Neptune balls on different beaches on Mallorca, chosen for its extensive meadows of Posidonia oceanica and its large accumulations of plastic waste.[15] The study found that:[15]

Plastic debris in loose leaves (wracks) were found in 50% of the samples, with up to 613 plastic items per kg of dead leaves. Plastic items consisted mostly of fragments (61.29%) followed by pellets (33.67%) and foams (2.90%). The polymers were identified by spectrometry and included polyethylene (PE) (50.57%) followed by polypropylene (PP) (32.18%) and polyvinyl chloride (PVC) (6.90%). Plastic sizes ranged from 0.55 to 287 mm and averaged 9.08 mm.

Neptune balls may collect up to 900 million pieces of plastic from the ocean every year.[3] It is unclear whether the plastic damages the seagrass specifically.[3] After the paper was published, Anna Sanchez-Vidal, a researcher at the University of Barcelona and lead author of the paper, received pictures of Neptune balls filled with plastic.[2] In an interview with the BBC, she said that these examples contained larger plastics like "sanitary towels, tampons, [and] wet wipes".[2] Sanchez-Vidal stated that the Neptune balls return "trash to us that was never meant to be on the seafloor".[2] However, Neptune balls are not a solution for plastic waste problems, as removing them to reduce pollution would disrupt the beach ecosystem, and they would not work as a plastic filter.[2]

A 2024 study by the Spanish Institute of Oceanography found that Neptune balls are an effective indicator for marine plastic pollution on the seafloor, especially microplastics, which were present in 62% of collected Neptune balls containing plastic. However, the study suggested that more research is needed to assess what proportion of plastics in Neptune balls are fibres, in order to assess differences between plastics found on beaches compared to on the sea floor.[4] Additionally, the study found that Neptune balls may facilitate the movement of plastic from the seafloor to the surface, which could lead to increased consumption of plastic by sea life.[4] The study concluded that the number of plastic items trapped in Neptune balls is dependent on the number of plastic items in the area rather than the size of the balls.[4]

A 2026 study suggested that Neptune balls offer "promising opportunities for large-scale [plastic pollution] monitoring programs", although the method is still "in an early stage" and "[f]urther research is required" to standardise Neptune balls as an indicator of marine plastic pollution.[6] The study analysed 1300 Neptune balls collected on 13 beaches of the Latium coast, and found that more than one-third contained plastic, with microplastics being the most common type.[6]

Footnotes

[edit]
  1. ↑ Meaning "marine ball of yarn". Another name in French is "aegagropiles de mer" or "aegagropiles marines", meaning "sea aegagropiles".[10][11]
  2. ↑ Other names in German include Meerballen, Meerbälle and Meerpillen.[7]
  3. ↑ Archaically written as ſea balls.[12]
  4. ↑ German: unechte.
  5. ↑ German: echte.
  6. ↑ Some Neptune balls have a nucleus, though this is not needed to create them.[1]
  7. ↑ The mean radius varies depending on the axis. The mean length of each axis is 2.681, 1.449, and 1.146, respectively. The geometric standard deviation for each axis is 1.436, 1.47, and 1.458, respectively.[1]
  8. ↑ With a geometric standard deviation of 1.458.[1]

References

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  1. 1 2 3 4 5 6 7 8 9 10 11 12 13 Verhille, Gautier; Moulinet, Sébastien; Vandenberghe, Nicolas; Adda-Bedia, Mokhtar; Le Gal, Patrice (17 April 2017). "Structure and mechanics of aegagropilae fiber network". Proceedings of the National Academy of Sciences of the United States of America. 114. National Academy of Sciences. doi:10.1073/pnas.1620688114.
  2. 1 2 3 4 5 6 7 8 9 10 11 12 13 Adkins, Frankie (2 September 2025). "'It's a way of the sea returning the trash to us': Why plastic-filled 'Neptune balls' are washing up on beaches". BBC. Retrieved 21 February 2026.
  3. 1 2 3 4 "Seagrass 'Neptune balls' sieve millions of plastic particles from water, study finds". Agence France-Presse. The Guardian. 15 January 2021. Retrieved 23 February 2026.
  4. 1 2 3 4 Alomar, Carme; Compa, Montserrat; Fagiano, Valentina; Concato, Margherita; Deudero, Salud (December 2024). "Posidonia oceanica egagropiles: Good indicators for plastic pollution in coastal areas?". Regional Studies in Marine Science. 77. Elsevier. doi:10.1016/j.rsma.2024.103653. ISSN 2352-4855 – via Elsevier Science Direct.
  5. 1 2 3 4 Restaino, Odile Francesca; Giosafatto, Concetta Valeria L.; Mirpoor, Seyedeh Fatemeh; Cammarota, Marcella; Hejazi, Sondos; Mariniello, Loredana; Schiraldi, Chiara; Porta, Raffaele (14 April 2023). "Sustainable exploitation of Posidonia oceanica sea balls (egagropili): A review". International Journal of Molecular Sciences. 24 (8). MDPI: 7301. doi:10.3390/ijms24087301. ISSN 1422-0067. PMC 10138933. PMID 37108463.
  6. 1 2 3 Menegoni, Patrizia; Pietrelli, Loris (25 January 2026). "The role of Posidonia oceanica spheroids in assessing microplastic contamination in coastal ecosystems". Environments. 13 (2). MDPI: 71. doi:10.3390/environments13020071. ISSN 2076-3298.
  7. 1 2 3 4 5 6 7 8 9 10 11 12 13 Schröder, Bruno (October 1920). "Über Seebälle". Naturwissenschaften (in German). 8. Springer Science+Business Media: 799–803. doi:10.1007/BF02450052.
  8. 1 2 3 4 Croneis, Carey; Grubbs, David M. (1939). "Silurian sea balls". The Journal of Geology. 47 (6): 598–612 – via JSTOR.
  9. ↑ "Définitions : pelote-de-mer". Dictionnaire de français Larousse. Retrieved 1 March 2026.
  10. 1 2 Weddell, Hugh Algernon (1877). Actes du Congrès international de botanistes, d'horticulteurs, de négociants et de fabricants de produits du règne végétal: tenu à Amsterdam, en 1877. Actes du Congrès international de botanistes, d'horticulteurs, de négociants et de fabricants de produits du règne végétal (in French). pp. 58–62.
  11. 1 2 3 4 5 6 Ganong, W. F. (August 1909). "On balls of vegetable matter from sandy shores. (Second article)". Rhodora. 11 (128): 149–152. ISSN 0035-4902 – via JSTOR.
  12. 1 2 3 4 Encyclopédie. Vol. 12. p. 263.
  13. 1 2 3 Minchin, Dan (22 June 2018). "'Sea balls' on Inch Strand, Co. Kerry (H 1)". The Irish Naturalists' Journal. 36 (1): 25–27 – via JSTOR.
  14. 1 2 Ganong, W. F. (March 1905). "On balls of vegetable matter from sandy shores". Rhodora. 7 (75): 41–47 – via JSTOR.
  15. 1 2 3 4 5 6 7 8 9 10 Sanchez-Vidal, Anna; Canals, Miquel; de Haan, William P.; Romero, Javier; Veny, Marta (14 January 2021). "Seagrasses provide a novel ecosystem service by trapping marine plastics". Scientific Reports. 11 (1). Nature Portfolio. doi:10.1038/s41598-020-79370-3. ISSN 2045-2322. PMC 7809288. PMID 33446674.  This article incorporates text available under the CC BY 4.0 license.
  16. ↑ Lefebvre, Laurence; Compère, Philippe; Gobert, Sylvie (January 2023). "The formation of aegagropiles from the Mediterranean seagrass Posidonia oceanica (L.) Delile (1813): plant tissue sources and colonisation by melanised fungal mycelium". Marine Biology. 170 (2). doi:10.1007/s00227-022-04166-0. ISSN 0025-3162.
  17. 1 2 3 4 5 6 Khiari, Ramzi; Jawaid, Mohammad, eds. (31 May 2025). Current Status and Opportunity in Fibre and Composites: Posidonia Oceanica. Springer Nature. ISBN 981-96-4546-8.
  18. 1 2 Pompoli, Francesco (4 April 2023). "Acoustical characterization and modeling of sustainable Posidonia fibers". Applied Sciences. 13 (7). MDPI: 4562. doi:10.3390/app13074562. hdl:11392/2515950. ISSN 2076-3417.
  19. 1 2 Petruch, Markus; Walcher, Dominik (2025). Circular Bioeconomy: 101 Renewable Innovations (1st ed. 2025 ed.). Cham: Springer Nature. ISBN 978-3-031-95925-7.
  20. ↑ "Saving Mediterranean Posidonia". WWF. Retrieved 27 February 2026.
  21. ↑ Olson, F. C. W. (March 1957). "A seaball from Escambia County, Florida". Quarterly Journal of the Florida Academy of Sciences. 20 (1). Florida Academy of Sciences, Inc.: 93–94 – via JSTOR.
  22. 1 2 Vasarri, Marzia; De Biasi, Anna Maria; Barletta, Emanuela; Pretti, Carlo; Degl'Innocenti, Donatella (25 August 2021). "An overview of new insights into the benefits of the seagrass Posidonia oceanica for human health". Marine Drugs. 19 (9). MDPI: 476. doi:10.3390/md19090476. ISSN 1660-3397. PMC 8470915. PMID 34564138.
  23. ↑ "Posidonia caulini". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 4 March 2026.
  24. ↑ Bulletin de la Société d'Étude des Sciences Naturelles de Reims (in French). 1897. pp. 26–27.
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