Insight :Seashells are hard, protective outer layers created by marine animals or organisms, such as mollusks, that live in the sea.

Insight :Seashells are secreted by the mantle, a thin layer of tissue that covers the animal's body, and grow incrementally at the shell margin.

Insight :Seashells can have different microstructures, such as nacre or mother-of-pearl, which is an iridescent inner layer found in some shells.

Insight :Seashells are not used by all mollusks, as some members of the cephalopod family, such as octopuses and squids, do not have shells or have reduced shells.