The blue mussel (Mytilus edulis), also known as the common mussel,[1] is a medium-sized edible marine bivalve mollusc in the family Mytilidae, the only extant family in the order  Mytilida, known as "true mussels". Blue mussels are subject to commercial use and intensive aquaculture. A species with a large range, the blue mussel leaves empty shells that are commonly found on beaches around the world.