Mollusc shell
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The mollusc 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.
Diversity and variability of shells of molluscs on display.
Variety of Mollusc shells (gastropods: land snail shells and seashells).
Closed and open shells of a marine bivalve, Petricola pholadiformis. A bivalve shell is composed of two hinged valves which are joined by a ligament.
Four views of a shell of the land snail Arianta arbustorum
Mantle (mollusc)
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The mantle is a significant part of the anatomy of molluscs: it is the dorsal body wall which covers the visceral mass and usually protrudes in the form of flaps well beyond the visceral mass itself.
European squid (Loligo vulgaris). The mantle is all that is visible behind the head: the outer body wall and the fins are all part of the mantle.
The brightly coloured mantle of a giant clam protects it from bright sunlight.
The cuttlefish uses its mantle cavity for jet propulsion
The marine gastropod Cypraea chinensis, the Chinese cowry, showing its partially extended mantle.