Cowries (esp. Cypraea moneta) were used as a currency in Africa (e.g., Nigeria) and elsewhere. They are also worn as jewelry or otherwise used as ornaments or charms, as they are viewn as symbols of womanhood, fertility, birth and wealth. (And the shiny, porcelain-like shells are simply pleasing to look at.)
Cowry shells are sometimes used in a way similar to dice, e.g., in board games like Pachisi, or in divination (cf. the annual customs of Dahomey). A number of shells (6 or 7 in Pachisi) are thrown, with those landing appeture upwards indicating the actual number "rolled".