It can reach 20 centimeters in length but always remains flat. The pipa pipa is a completely flat South American toad. Even more amazing: his offspring are born by expelling themselves from his back. Each pipa pipa has a hundred holes in the skin on its back. At the time of reproduction, each of its holes is inhabited by a tadpole. Three months later, this tadpole, which has become a small toad, expels itself from its mother's back.