Placunidae, also known as windowpane oysters, windowpane shells, and Capiz shells, are a taxonomic family of saltwater clams, marine bivalve mollusks which are related to oysters and scallops.
This family is best known for the shells of the species Placuna placenta, which are translucent, and are commonly used in shellcraft production. In some cultures, they were used as a form of light-admitting window.
The family is closely related to the Anomiidae (saddle oysters). One of the main differences is that the Placunidae do not attach themselves to a hard surface but are instead a mud-living family.