Yep Island's huge coins

Yep Island in Micronesia, in the Pacific Ocean, uses the US dollar as its official currency, but they also use another unusual currency: large limestone discs, some weighing as much as a car. These discs are plentiful there, and thieves cannot steal them due to their size.

Source

https://www.npr.org/sections/money/2011/02/15/131934618/the-island-of-stone-money?fbclid=IwAR1jeyPGW9cbb6G2uGY1Slr6tA1Dy1PjvOr_LdrRnG3ryZJ62fA83sZ2HWU