A penis would rank pretty high on any list of body parts you'd want to be able to grow back if lost. The more replacement penises the better. And for the first time, Japanese biologists have found an animal that can do just that.
What makes this slug so ninja-like? Because these slimy fellers shoot chalky "love darts" at potential mates which pierce and inject the proper hormones to make them hot and horny. Hmm..maybe it should be called the Roofie Slug, instead?