What is "sea silk"

n. An extremely fine, rare and valuable fabric produced from the long silky filaments or byssus excreted by several molluscs (particularly (taxlink Pinna nobilis species noshow=1)) by which they attach themselves to the sea bed.

Sea silk is an extremely fine, rare, and valuable fabric that is made from the long silky filaments or byssus secreted by a gland in the foot of pen shells (in particular Pinna nobilis). The byssus is used by the clam to attach itself to the sea bed.

Sea silk was produced in the Mediterranean region from the large marine bivalve mollusc Pinna nobilis until early in the 20th century. The shell, which is sometimes almost a metre long, adheres itself to rocks with a tuft of very strong thin fibres, pointed end down, in the intertidal zone. These byssus or filaments (which can be up to 6 cm long) are spun and, when treated with lemon juice, turn a golden colour, which never fades.

The cloth produced from these filaments can be woven even finer than silk, and is extremely light and warm; however, it attracts clothes moths, the larvae of which will eat it. It was said that a pair of women's gloves made from the fabric could fit into half a walnut shell and a pair of stockings in a snuffbox. In addition, Pinna nobilis is also sometimes gathered for its flesh (as food) and occasionally has pearls of fair quality.