Pictured above are examples of the 'Money Cowrie', a seashell commonly found in the Indian ocean. Shells have been used as money in most continents for thousands of years, with the financial incentive being collect them in large numbers from where they are common. (IE, the Maldives) and ship them to where they were much less common. (IE. West Africa) and trade them at a huge profit. This practice continued well into the 19th century.
For example, one African tribal king's revenue was estimated at 30,000,000 shells, with every adult male being required to pay annually 1000 shells for himself, 1000 for every pack-ox, and 2000 for every slave in his possession.
Often strung together as necklaces or bracelets. They made very useful small change. The items pictured came to me as part of an old coin collection, and not from a packet purchased on Clacton pier! I believe them to be genuine traded shells.