CowriesCypraeidae

A cowrie shell is glossy because it is never left bare. The living animal spreads two flaps of mantle up and over the outside of the shell until they meet along the top, and those flaps keep laying down fresh enamel on the outer surface. The shell is being resurfaced from the outside for as long as the snail is alive, which is why nothing settles or grows on it and why scratches disappear. It is also why a cowrie at night looks like a wet lump studded with fleshy papillae, with no shell visible at all, until your light hits it and ten seconds later it is bare and polished.

The shape is a snail shell that swallowed itself. The last whorl wraps around all the earlier ones and buries the spire completely, and the opening is squeezed down to a long slit with teeth along both sides, too narrow for most things to get into. Young cowries look nothing like this: thin, pale, wide mouthed, closer to a bubble shell. At maturity the animal stops adding length, rolls the lip inward, cuts the teeth and thickens the whole shell. Growth ends there, and an adult cowrie never gets any bigger.

The surface has a word named after it. Italian traders called these shells porcellana, after the curved back of a little pig, and when a hard white glazed ceramic arrived from 🇨🇳 China that felt the same under a thumb, it inherited the shell's name. That is where porcelain comes from.

Two of the small ones were money. Cowries were shipped by the ton out of the 🇲🇻 Maldives to West Africa and across Asia and used as currency for centuries, in places that coins reached much later, which is how the money cowrie and the ring cowrie got their names. Both live on this coast, along with larger species that spend the day jammed into a crack under rock and come out after dark.