Blue Mussel - Mytilus edulis

At the upper left, you can see the mussel's byssal threads. Byssal threads are secreted as a liquid by a gland near the mussel's foot, and then the threads harden upon contact with water. They are pretty strong, but can be ripped if you pull hard enough. They allow the mussel to anchor itself to nearly any surface.

Habitat: Tidal pools during low tide