Seashells, sea shells or simply shells are the protective exterior form of an animal called an exoskeleton, most often from a mollusk. But other animals besides mollusks make shells, such as horseshoe crabs, true crabs, and sea urchins, called a “test”. Some animals in the ocean which don’t have an exoskeleton to protect them will use an empty seashell for cover, such as a hermit crab. Even an octopus, also a mollusk, will use a discarded shell for cover.
Humans have...
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