English: An eastern and western Atlantic mollusk of Cardiidae family. The valve on the left is from the European coasts and the species is Acanthocardia tuberculata (Linnaeus, 1758)[1], the Tuberculate Cockle; the valve on the right is from the American coasts and the species is Dallocardia muricata (Linnaeus, 1758), the American Yellow Cockle; during the 20th century called Trachycardium muricatum (Linnaeus, 1758)[2].

• ABBOTT, R. Tucker; DANCE, S. Peter (1982). Compendium of Seashells. A color Guide to More than 4.200 of the World's Marine Shells. New York: E. P. Dutton. p. 327. 412 pp. ISBN 0-525-93269-0

(The image is a little distant because it was not generated with enough clarity to be approximate, in the opinion of its creator).