Fan mussel  (Atrina fragilis)

Growing to an impressive 48 cm in length (2), the fan mussel (Atrina fragilis) is one of the largest of the bivalve molluscs found in Europe (3). It takes its English name from the delicate shell, which is triangular in shape, and tapers to a point. The valves of the shell are pale yellowish-brown to dark brown in colour, with a glossy interior. Living specimens are partly buried vertically in the sediment, with only the top portion of the valves visible. Fan mussels anchor themselves into the sediment by attaching to small stones with numerous fine strands of protein known as 'byssus'. The byssus of this species is so like human hair that many fishermen believed that fan shells had fed upon drowned people. They therefore deemed this species 'unclean', and would return them to the sea if they were caught (2).