In the late 19th century CE Sierra Leone and surrounds, high quality iron needles tied into bundles served as currency.
Most of the world has settled on coins and banknotes as the way to create physical currency. But history provides us with many alternatives: shells, stones, beads, rings, chain links, bands, even blocks of salt. But the so-called “kissi pennies” of Sierra Leone and surrounding countries are an especially interesting one.
First, they’re made of high-quality iron rather than precious metal. Second, they’re in the shape of long knitting-needles or nails with a flat shovel-shaped head and a spiky T on the other end. This is pretty clever: unlike coins, where you could shave off or clip the edges to gather metal, there’s no easy way to extract free iron from a kissi penny without undermining the essential shape of the object. Third, while the value of an individual penny was low, it was very easy to tie them into bundles that served as more valuable currency: in the early 20th century a cow might cost a two thousand kissi pennies, or a hundred bundles of twenty.