Byssus are the silky threads by means of which many bivalves attach themselves to a firm surface. The byssus threads are secreted in a gland in the foot which is the homologue of the mucusgland of the snail, and can be speedily renewed if severed. They are seen in very simple form in the common edible mussel (Mytilus), which is always attached to its surroundings by a tuft of golden threads. Research Byssus