I’m becoming a bit of a Karl Myself -
Apparently Monkeys and Chimpanzees can be taught the value of money and naturally value crystals.
No, true, and some of the monkeys were seen to use money to buy sex...
Anyways, a curious world we live in. Here are a couple of AI links you can explore:
Link: Chimpanzees & Capuchin Monkeys learning how to use money
Link: Chimpanzees and Crystals
And, on a related note, Otters have a favourite rock, but where as the Crystals served no function the Otters use the rock as a tool.