Byssus
A byssus is a bundle of filaments secreted by many species of bivalve mollusk that function to attach the mollusk to a solid surface. Species from several families of clams have a byssus, including the pen shells, the true mussels and the false mussels: the Pinnidae, the Mytilidae and the Dreissenidae. Byssus cloth is a rare fabric, also known as sea silk, that is made using the byssus of pen shells as the fiber source.
