Solid Ark Shell, Arcopsis solida

Solid Ark, Arcopsis solida.  Size: 1.9 cm (0.7 inches) x 1.1 cm (0.4 inches). Shell collected from within a tidal pool at El Tule, Km 17, Baja California Sur, October 2018.

The Solid Ark, Arcopsis solida (G.B. Sowerby I, 1833), is a bivalve mollusk that is a member of the Noetiidae Family of Arks, that is known in Mexico as arca diminuta. The shell is smaller and plumb with a rounded anterior end and a  slightly sloping posterior end. The surface is covered with radiating fine lines. The shell is yellowish white in color. The Solid Ark Shell reach 1.9 cm (0.7 inches) in length and 1.1 cm (0.4 inches) in height.

Solid Arks are found attached to rocks in the intertidal zone to depths of 50 m (165 feet). They range from Southern California to Peru. They are found throughout the Sea of Cortez.

Synonyms include Barbatia diguetid and Byssoarca solida.