What are those brown balls on Mallorca’s beaches?
Neptune balls on the beach in Mallorca. Bottom right shows how it grows (before it forms the ball), bottom left a ball that has been plucked apart and on the top a neptune ball like you see them all over the balearic beaches. (Photo courtesy of)
Winter arrival
Every winter the storms bring round, brown, pingpong sized balls onto our beaches. Accompanied by green grass looking leaves that pile up meters high sometimes. After a while the piles dry out and in spring the local governments clear the beaches of the grey dried out sea grass to get the beaches ready for tourism.
These brown balls will keep washing up on the beaches during summer, so you have undoubtedly seen them. They are called Neptune balls (or egagropili), formed from Posidonia oceanica, an ancient seagrass vital to the Mediterranean ecosystem.
They form in the same way a dreadlock would, with the fibers of the (dead) grass being moved back and forth on the bottom of the sea, slowly compacting and rounding the balls.
Traditionially the washed up posidonia was used instead of hay in stables, as mulch in gardens and even as isolation in between walls!
🌍 Where Can You Find Them?
While most common in Mallorca, Ibiza, and other Mediterranean coasts, Neptune balls have also been spotted as far as Australia, the westcoast being the only other place on earth with Posidonia!
If the beach you are on seems cleaned, they can usually still be found at the far ends of the beach (where the piles of seagrass are pushed to) or along the edges of the beaches, where the sand meets the vegetation. Or you simply find them floating in the water if the wind is onshore. They are usually good for at least a couple of hours entertainment for children.
🌊 Mallorca’s Underwater Treasure
The Posidonia oceanica meadows in the Mediterranean sea cover around 25,000 and 50,000 km2 of the coastal areas, corresponding to 25% of the sea bottom at a depth between 0 and 40 m! Some of the Posidonia meadows are said to be between 80.000 and 200.000 years old. These underwater forests produce oxygen, clean the water, protect beaches from erosion, and support marine life.
So next time you see these odd brown balls on the beach, know they’re a sign of a thriving, healthy sea!
A posidonia meadow with the grass growing out of the brown fibrous stem.