What’s this curiosity I found at the seaside?

Last week’s curiosity was heather, which comes into flower on the Moors of Northern England in the
Autumn (fall). It’s a food source for deer, sheep and grouse which like to feed on the young shoots.

In the middle-ages heather, along with malt, was used in the brewing of beer until it was later replaced by the use of hops.

Heather

For the next few weeks my curiosities will come from a trip to the seaside. Can you identify this wobbly creature I saw?