Pronunciation: (ku-pēz', ka-),[key] —n. 1. a small marine bivalve of the genus Placuna, esp. P. placenta, common in Philippine coastal waters and some other parts of the Pacific Ocean.
2. Also called windowpane shell, windowglass shell. the squarish, translucent inner shell of Placuna used in making lamps, windowpane, and decorative objects.