Aulacomya atra, called also the Magellan mussel[2] or the ribbed mussel,[1][3] is a southern species of edible saltwater mussel, a marine bivalve mollusk in the family Mytilidae, the true mussels.[1] Note that the common name ribbed mussel is also used of the Northern Hemisphere mussel Geukensia demissa.
Aulacomya atra is native in South America - in Peru, Chile (where it grows up to 170 mm in length), the Falkland Islands and Argentina.[2] It is also found on the coasts of New Zealand and southern Africa, from Namibia to Port Alfred, South Africa, from the intertidal to 40 m.[3] Introduced specimens have been found in Moray Firth, Scotland.[2]In Southern Africa the species grows up to 90 mm in length. It usually lives in crowded intertidal beds. Individual animals have brown ribbed shells, which darken to black with age.[4]