No one knows exactly when the people of Yap, a tiny Micronesian island, started using giant limestone disks as money, but their unique stone money have definitely been around for centuries and are still in circulation today.
Micronesian islands use the US dollar as their official currency, but on the island of Yap people also use a very unusual form of money – giant limestone discs, some of which weigh more than a car. There are hundreds of these discs scattered all over the island, some located outside of hotels, others stored deep in the forest, but most of them are kept in stone money banks located in virtually every village. There are an estimated 13,000 stone discs in circulation on Yap, ranging from 30 centimetres to 3.50 meters in diameter, with the largest ones being considered the most valuable.