Whilst other creatures of this kind are eaten; various kinds of 'sea cucumber' are eaten in China and the edible sea urchin is a familiar sight in Mediterranean restaurants; nowhere does it appear that the 'sea potato' is eaten.That's not to say it can't be eaten , only that nobody seems to think it worthwhile getting it out of its burrow to eat it !
Its common name is from its looking like a potato when it gets washed up ashore.By that time it has lost its spines and is smooth.