Have you ever seen them? They're seed pods that look like small beans. Larvae of small moths chew their way inside the beans. The larvae don't like heat, so when the beans become too hot, the larvae "jump" as they try to find a cooler spot. The beans are native to Mexico, hence the name Mexican Jumping Beans.
I didn't know that these beans existed until very recently. When I was a kid, I had a toy that was called a Mexican Jumping Bean. It looked like a pill capsule and had something inside of it that would make it twitch. I remember that I enjoyed playing with it, but if I had known there were real jumping beans available for purchase, I'm sure I would have been begging my parents to buy some!
Have you ever owned Mexican Jumping Beans, real or fake?