Mother-of-pearl is the hard, silvery, internal layer of several kinds of shells, especially oysters, the large varieties of which in the Indian Seas secrete this coat of sufficient thickness to ...

"Looked at one way, a racing shell is a machine with a narrowly defined purpose: to enable a number of large men or women to propel themselves over an expanse of water as quickly and efficiently ...

These crustaceans have been misnamed for two reasons: First, they’re not true crabs, like blue crabs, in that they don’t have a uniformly hard exoskeleton and can’t grow their own shells.