Common whelk egg mass, Buccinum undatumSometimes called ‘Seawash balls’, whelk eggcases are often found washed up on the beach in winter. Sailors once used them to wash with, hence their common name. However they are the empty eggcases laid by the common whelk, a large sea snail with the iconic seashell shape. The ‘ball’ is made up of dozens of pockets, each containing ten or more eggs.

Most of the eggs are eaten by the first one to hatch before it emerges from the case. Normally the egg-masses are grey in colour and empty of eggs when they wash onto the beach, but in rough weather they are sometimes thrown up before they are all hatched and are still yellow.

Volunteers found this massive structure, standing half a meter high, and still intact, in the seagrass.