Bulk Capiz Shells For Crafts, windowpane oyster shells, a flat sea shell, measuring approximately 2-1/2 inches. Capiz shell is a flat, semi-transparent sea shell with a pearlescent appearance. It is  used in making capiz shell chandeliers, inlaid furniture, capiz shell trays, bowls, picture frames, capiz shell ornaments and more. Many hotels feature capiz panels on the interior walls of their lobbies and hallways.  The windowpane oyster is a bivalve marine mollusk in the family Placunidae.   They are edible, but valued more for their shells. The shells have been used for thousands of years as a glass substitute because of their durability and translucence.