Due to pressure of work, visitors, holidays and rotten weather, haven't had time to post in the last couple of months. However, yesterday was a lovely warm and sunny day, so headed early to the beach. It was low tide and I found several of these strange looking objects. They were very fragile and some were broken. I thought they might be the test of a sea urchin, and on looking them up found that they are known as sea-potatoes, only they are animal not vegetable. They are known as heart-urchins due to their shape. They are adapted for burrowing and are usually found about 15cm deep in the sand (perhaps that's why they are known as sea-potatoes). When alive they are densely covered in yellow-brown spines.