Wikipedia
Shell money is a medium of exchange similar to money that was once commonly used in many parts of the world. Shell money usually consisted either of whole sea shells or pieces of them, which were often worked into beads or were otherwise artificially shaped. The use of shells in trade began as direct commodity exchange, the shells having value as body ornamentation. The distinction between beads as commodities and beads as money has been the subject of debate among economic anthropologists.
Some form of shell money appears to have been found on almost every continent: America, Asia, Africa and Australia. The shell most widely used worldwide as currency was the shell of Cypraea moneta, the money cowry. This species is most abundant in the Indian Ocean, and was collected in the Maldive Islands, in Sri Lanka, along the Malabar coast, in Borneo and on other East Indian islands, and in various parts of the African coast from Ras Hafun to Mozambique. Cowry shell money was important at one time or another in the trade networks of Africa, South Asia, and East Asia.