wing-shell

from The Century Dictionary.

• noun A gastropod of the family Strom-hidæ: so called from the alate lip of the aperture. See also cut under Strombus.
• noun A bivalve of the family Aviculidæ; a hammer-oyster.
• noun A pteropod or wing-snail.
• noun A wing-case or wing-cover.

from the GNU version of the Collaborative International Dictionary of English.

• noun Any one of various species of marine bivalve shells belonging to the genus Avicula, in which the hinge border projects like a wing.
• noun Any marine gastropod shell of the genus Strombus. See strombus.
• noun Any pteropod shell.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Any of various species of marine bivalve shells belonging to the genus Avicula, in which the hinge border projects like a wing.
• noun Any marine gastropod shell of the genus Strombus.
• noun Any pteropod shell.