There are a lot of movies about scientists who inadvertently create beasts that go on to break out of labs and wreak havoc on the world. Real researchers do that too, only with more specific intentions and fewer apocalyptic outcomes. Over the years, they’ve created mutant ants, glowing bunnies, and a human-pig chimera. They’ve even created a human ear on the back of a mouse. Many were done to gain a greater understanding of illnesses and make effective treatments.