WHAT IS A MEXICAN JUMPING BEAN?
The jumping bean is not a bean, nor is it a seed. It's actually a small, thin-shelled section of a seed capsule contining the larva of a small gray moth called the jumping bean moth. After consuming the seed inside of the capsule section, the robust, yellowish-white larva has the odd habit of throwing itself forcibly from one wall to the other. This is what causes the jumping movements of the capsule.
Mexican jumping bean capsules typically separate into three sections, some of which contain a moth larva. It's thise separate sections, called carpels, that are sold as jumping beans.