Definition:
Byssal, or byssus threads are strong, silky fibers made from proteins that are used by mussels and other bivalves to attach to rocks, pilings, or other substrates. These animals produce their byssal threads using a byssus gland, located within the organism's foot. Mollusks can move slowly by extending a byssal thread, using it as an anchor and then shortening it.
The byssal threads from some animals, such as the pen shell were once used to weave into a golden cloth.
To seafood enthusiasts, these threads are known as the animal's "beard," and are removed before cooking.
Also Known As: Byssus threads, the beard
Examples:
Mussels form large colonies by attaching to each other using their byssal threads.
