![]() ![]() ![]() ![]() The many different types, colours and shapes of pearls depend on the natural pigment of the nacre, and the shape of the original irritant. Over the years, the irritating object is covered with enough layers of nacre to become a pearl. In nature, pearl oysters produce pearls by covering a minute invasive object with nacre. Not all individual oysters produce pearls naturally. The largest pearl-bearing oyster is the marine Pinctada maxima, which is roughly the size of a dinner plate. Both cultured pearls and natural pearls can be extracted from pearl oysters, though other molluscs, such as the freshwater mussels, also yield pearls of commercial value. Pearl oysters are not closely related to true oysters, being members of a distinct family, the feathered oysters ( Pteriidae). Pearls can form in both saltwater and freshwater environments. Pearl oysters Īlmost all shell-bearing mollusks can secrete pearls, yet most are not very valuable. Ostreidae evolved in the Early Triassic epoch: The genus Liostrea grew on the shells of living ammonoids. Examples include the European flat oyster, eastern oyster, Olympia oyster, Pacific oyster, and the Sydney rock oyster. This family includes the edible oysters, which mainly belong to the genera Ostrea, Crassostrea, Ostreola, Magallana, and Saccostrea. True oysters are members of the family Ostreidae. The French derived from the Latin ostrea, the feminine form of ostreum, which is the latinisation of the Ancient Greek ὄστρεον ( ostreon) 'oyster'. The word oyster comes from Old French oistre, and first appeared in English during the 14th century. ![]()
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