Sea silk is a rare textile made from byssus, silky filaments made of proteins hardened upon contact with seawater secreted by mollusks to attach themselves to the sea bed. The Pinna nobilis (aka pen shells), which can be up to a metre in length and are found in the Mediterranean sea, produce byssus filaments that have been spun and treated with lemon juice to produce a golden colour thread that never fades. The resulting textile is extremely fine and has been historically used to weave and knit garments including gloves and stockings.
The Chinese recorded importing ‘mermaid silk’ from the west as early as the 3rd century, and by the 5thcentury there were Roman edicts limiting who could wear garments made of lana pinna. More recent references to sea silk include the crew of the Nautilus in Jules Verne’s 1870 novel 20,000 Leagues Under the Sea, who wore clothes made of ‘seashell tissue’.
The Pinna nobilis is now a threatened species due to overfishing and habitat destruction. A few women on the island of Sant’Antioco near Sardinia still make sea silk, but harvesting Pinna nobilis byssus is now protected by the Italian coast guard, and fabric made from byssus cannot be bought or sold.