Ribbed Mussel (Geukensia demissa)
Family: Mytilidae
Geukensia demissa (Dillwyn, 1817)
Synonyms: Modiolus demissus (Dillwyn), Modiola plicatula (Lamarck), Volsella demissa (Dillwyn)
The ribbed mussel (see below) is found regularly on South Hutchinson Island where I have collected several hundred shells. It is a 3" or less light brown shell with detailed ribs erxtending from the umbone. The back is highly refelctive.