Oyster is the common name for a number of different families of salt-water bivalve molluscs that live in marine or brackish habitats. In some species the valves are highly calcified, and many are somewhat irregular in shape. Many, but not all, oysters are in the superfamily Ostreoidea. Some kinds of oysters are commonly consumed by humans, cooked or raw, the latter being a delicacy. Some kinds of pearl oysters are harvested for the pearl produced within the mantle. Windowpane oysters are harvested for their translucent shells, which are used to make various kinds of decorative objects. First attested in English during the 14th century, the word "oyster" comes from Old French oistre, in turn from Latin ostrea, the feminine form of ostreum, which is the latinisation of the Greek ?st?e?? (ostreon), "oyster". Compare ?st??? (osteon), "bone".