Transverse Ark

Shell size to 40 mm; shell oblong, inequivalve, with left valve larger, overlapping right valve. Hinge straight. Sculpture of 30-35 radial ribs. Smallest species in genus Anadara. Periostracum dark-brown. Color white. This species has been reported in an 2012 article published by Susan Hewitt in The Festivus as the most common shell found on Sanibel beaches.