Until the 20th century, the people of the Pacifc island of Yap used large stone discs called rai as money. These were usually used in social transactions such as marriage and ransom. The rai, which weighed as much as four tons, were rarely moved. Rather, everyone knew who the owner of a particular rai was. The rai were cut in Palau, an island 280 miles away, and transported by canoes. One of the rai was dropped into the ocean while being transported. It was still recognized as money.
From the September 2011 issue of Happiness Pony. [PDF]