As a kid, I played with "rock money" in the backyard. If it was igneous, it was money. We traded (mostly other rocks) using this rock money. Eventually, we found all of the rocks we were basically ever going to find in our collective yards.

Then someone — I think it was me — declared that white limestone rock was also money, because we didn't have enough rock money in reasonable sizes to trade. That was frustrating for those with lots of rock money, because suddenly their cool multicolor rocks weren't highly prized, they were just as special as lame normal white rocks that were abundant.

It was annoying that our rocks were devalued by a new influx. But we needed the influx to have a functional economy. The issues with the rock sizes and just wanting to *keep* some of the rocks, was preventing us from actually making deals with each other. And... it was always possible someone would go camping near a creek and come back with more money, which came across with the same unfairness as arbitrarily saying limestone is money, too.

But in practice, the influx didn't hurt us much. We still all had money and could trade, and that was really all the money was for.

I guess not long after that, we stopped trading with rocks.

I think the game wasn't as fun when anybody could decide any rocks were money. Limestone had been chosen because it was abundant, but that left a lot fewer rocks to trade for. There was very little else in our economy to value.