Mexican jumping beans are a prank store classic- a packet full of “beans” that move and jump around on their own which pranksters use to startle their victims.
They're generally sold without explanation or list of ingredients, their packages claiming they "work like magic" in order to perpetuate the myth.
But how does this classic prank actually work?
The jumping is actually the moth larva moving inside the seed, which it will do for months until it finally spins a coccoon and undergoes a metamorphosis into an adult Jumping Bean moth.
-Via Laughing Squid