It's an oyster.

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Species Profile:

The oyster, also known as oyster, oyster (Cantonese region), oyster (southern Fujian region), also known as sea oyster, oyster yellow, oyster white, green oyster, oyster, oyster clam, oyster clams, oyster, belongs to the phylum Mollusca, class Bivalvia. Oysters are produced in seawater or at the junction of salt and fresh water, and feed on plankton. In Chinese medicine, oyster shells are used as medicinal herbs and ground into a powder called "oyster".

Habitat

Habitat

Oysters live in hard areas of the sea floor called oyster beds, which are located in deep or shallow seawater or salty estuarine waters. Oysters live in the middle intertidal zone.

Food habits

Oyster fixation shellfish. Generally fixed in the shallow sea objects or seaside reefs, to open and close the shell movement for feeding, respiration. It is a filter-feeding organism, taking tiny zooplankton, diatoms and organic debris as its main food. The oyster generates air currents in the water by vibrating the cilia on the gills, water enters the gills, and suspended particles in the water are stuck by the mucus. The cilia and tentacles on the gills sort the particles by size. Small particles are then delivered to the mouth and large particles are transported to the edge of the snare and thrown out.