Pinna nobilis, common name the noble pen shell or fan mussel, is a large species of Mediterranean clam, a marine bivalve mollusc in the family Pinnidae, the pen shells. It reaches up to 100 cm of shell length.
The bivalve shell is usually 30–50 cm long, but can reach 100 cm. Its shape differs depending on the region it inhabits. Like all pen shells, it is relatively fragile to pollution and shell damage. It attaches itself to rocks using a strong byssus. These keratin fibres that the animal secretes by its byssus gland can be up to 6 cm long. The inside of the shell is lined with brilliant mother-of-pearl.
This species is endemic to the Mediterranean, where it lives offshore at depths ranging between 0.5 and 60 m. It could be found buried beneath soft-sediment areas.
In recent years, Pinna nobilis has become threatened with extinction, due in part to fishing, incidental killing by trawling and anchoring, and the decline in seagrass fields; pollution kills eggs, larvae, and adult mussels. The noble pen shell has been listed as an endangered species in the Mediterranean Sea. The European Council, Habitats Directive 92/43/EEC, on conservation of natural habitats and the wild fauna and flora, proclaims that Pinna Nobilis is strictly protected all forms of deliberate capture or killing of fan mussel specimens are prohibited by law.
(extract from Wikipedia)