A small shellfish. Not all are edible, or worth the effort. The most common variety is the acorn barnacle. They include goose barnacles and goose-necked barnacles. I watched a delightful television programme with Billy Oddy, in which he drew the viewers' attention to a log which had drifted up on to a beach in the Scilly Islands. It was covered in silvery, shimmering goose barnacles. He said that he had never seen a goose barnacle before and that was because they were normally deep under the sea. He then lifted a single goose barnacle away from the hoard, showing a long and muscular "foot". As he lifted it, it became clear that it looked just like the delicate neck and head of a goose. He went on to explain that the Victorians had believed that, when geese set off on their migrations, they were actually travelling into the oceans, and that these goose barnacles, when they hatched, became geese and flew to land. There is, he reminded us, a goose called the barnacle goose.