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A black pearl and a shell of the black-lipped pearl oyster. The iridescent colors originate from nacre layers. All shelled mollusks can, by natural processes, produce some kind of "pearl" when an irritating microscopic object becomes trapped within its mantle folds, but the great majority of these "pearls" are not valued as gemstones.
A pearl is formed when the mantle tissue is injured by a parasite, an attack of a fish, or another event that damages the external fragile rim of the shell of a mollusk shell bivalve or gastropod. In response, the mantle tissue of the mollusk secretes nacre into the pearl sac, a cyst that forms during the healing process.
The iridescent nacre inside a nautilus shell Nacreous shell worked into a decorative object. Nacre (/ ˈ n eɪ k ər / NAY-kər, also / ˈ n æ k r ə / NAK-rə), [1] also known as mother-of-pearl, is an organic–inorganic composite material produced by some molluscs as an inner shell layer. It is also the material of which pearls are composed.
Cornu aspersum (formerly Helix aspersa)—a common land snail Shell of Marisa cornuarietis, a freshwater snail. Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks [a] (/ ˈ m ɒ l ə s k s /). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal ...
Pinctada is a genus of saltwater oysters, marine bivalve mollusks in the family Pteriidae. These pearl oysters have a strong inner shell layer composed of nacre, also known as "mother of pearl". Pearl oysters are not closely related to either the edible oysters of family Ostreidae or the freshwater pearl mussels of the families Unionidae and ...
The nautilus shell is composed of two layers: a matte white outer layer with dark orange stripes, [23] and a striking white iridescent inner layer. The innermost portion of the shell is a pearlescent blue-gray. The osmeña pearl, contrarily to its name, is not a pearl, but a jewellery product derived from this part of the shell. [citation needed]
This is a partial list of edible molluscs. Molluscs are a large phylum of invertebrate animals, many of which have shells . Edible molluscs are harvested from saltwater, freshwater, and the land, and include numerous members of the classes Gastropoda (snails), Bivalvia (clams, scallops, oysters etc.), Cephalopoda (octopus and squid), and ...
The mollusc (or mollusk [spelling 1]) shell is typically a calcareous exoskeleton which encloses, supports and protects the soft parts of an animal in the phylum Mollusca, which includes snails, clams, tusk shells, and several other classes. Not all shelled molluscs live in the sea; many live on the land and in freshwater.