West African Shell Money
Shell money was legal tender in West Africa until the middle of the 19th century, with the most common shell being the Cypraea moneta, or money cowry. Vast quantities of cowry shells were sent to English ports to use as payment in the slave trade. The value of the cowry was much greater in West Africa than elsewhere, so the profit margins were enormous. Even in Timbuktu, the famed City of Gold, cowry shells were in use as late as 1850.