byssus

byssus An exceptionally fine and valuable fibre or cloth of ancient times. Originally used for fine flax and linens, its use was later extended to fine cottons, silks, and sea silk.
The long fine silky filaments excreted by several mollusks (particularly (taxlink)) by which they attach themselves to the sea bed, and from which sea silk is manufactured.
puhekieltä The stipe or stem of some fungi which are particularly thin and thread-like.
English byssus