Were rocks once used for money?

Answer 1

Not very commonly. The idea of money is a rather advance concept and something precious was usually used. However, I remember seeing pictures of African tribes with large circular stones, each having a hole in the center, and the caption said something like stone money.

Answer 2

Yes, some societies have used rocks as a form of money, typically as part of a barter system where common or rare types of rocks were traded for goods or services. For example, large stone discs called Rai stones were used as currency by the Yap people in Micronesia.