The aye-aye, found in Madagascar  is a lemur of the size of a cat. It is the only primate which has six fingers. The sixth one is actually a pseudo thumb that acts as a sixth digit – possibly to help it hang onto trees in its Madagascar home. The sixth digit has been found by biologist Adam Hartstone Rose at his North Carolina State University lab.“It’s really cool to find this kind of anatomy in a primate for the first time, especially a primate as weird as an aye-aye,” Hartstone-Rose says. The wierd primate however is on endangered list.