What is a sea wash ball?

Q&A editor Sarah McPherson uncovers the mystery of a common beach find. 


Have you ever seen this mysterious object on the beach? © Steve Trewhella / Getty


This is a common find on the winter strandline, and is a baseball-sized sphere comprising a mass of empty common whelk egg cases.

It’s often seen attached to rocks or stones, and colour is significant: if it’s pale yellow, there may still be some eggs inside; if it’s greyish, the young will have left. Many of the hatchlings don’t survive, gobbled up by their stronger siblings.  

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