co qui na n. 1. Any of various small marine clams of the genus Donax that are common in the coastal waters of the eastern and southern United States and have variously colored, often striped or banded shells. 2.A soft, porous limestone, composed essentially of fragments of shells and coral, used as a building material. [Spanish, cockle, probably diminutive of concha, shell, from Latin, mussel. See CONCH.
(From the American Heritage Dictionary, Third Edition. Emphasis is ours.)