Pearls are natural or cultured gems produced by certain molluscs, most commonly bivalves like oysters (specifically pearl oysters). They form when an irritant, such as a parasite or a piece of shell, enters the mollusc and is covered by layers of nacre (mother-of-pearl) as a defense mechanism. While other molluscs can produce calcareous concretions, true pearls of commercial value are primarily associated with oysters and sometimes mussels. Prawns are crustaceans, Pila is a gastropod snail, and Tuna is a fish; none of these produce pearls.
Pearls are harvested from
Asked in UPSC CDS 2 2020 · Topic: Taxonomy (Concepts of Species and Other Taxa)
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