On Yap Island, in the Pacific Ocean, early inhabitants used large limestone disks, known as Rai stones, as money. Some of these disks weighed as much as a car! Everyone agreed that the stones were valuable and the people utilized them in much the same way we use money today. The weight of the stones and the fact that a Rai stone is difficult to split into smaller denominations would make Rai stones unfit to act as money today because Rai stones could not act as a ________.