wing-shell

Noun

 * 1) Any of various species of marine bivalve shells formerly belonging to the no longer accepted genus, now a synonym of Pteria, with species assigned to several genera, in which the hinge border projects like a wing.
 * 2) Any marine gastropod shell formerly in the genus, with species now assigned to several genera, principally in the family.
 * 3)  Any pteropod shell.