The Java mouse-deer (Tragulus javanicus) is neither a true mouse nor a true deer. Mouse refers to its small size; deer refers to its superficial deer-like body shape, which includes slender legs, large eyes, and a wedge-shaped head. Found in the dense tropical rainforests of the island of Java in Indonesia, is actually the world's smallest living hoofed mammal (ungulate). When it reaches maturity it is about the size of a rabbit.