Living fossils: Not too many creatures can claim to be “one of a kind,” but that’s a boast the tuatara can make. In fact, the tuatara is one of the most unique animals in the world. Although it looks like a lizard, it really is quite different. Found in New Zealand only, the tuatara’s closest relatives are an extinct group of reptiles around at the time of the dinosaurs. This is why some scientists refer to tuataras as “living fossils.”

Both male and female tuataras have a crest of spiky scales, called spines, down the center of their back and tail. Males are larger than the females. The name “tuatara” is a native Maori word meaning “peaks on back” or “spiny back.” Tuataras have no external ears as lizards do; they enjoy cooler weather, while lizards like it warm; and, unlike lizards, tuataras are nocturnal.

But their most curious body part is a “third eye” on the top of the head. The “eye” has a retina, lens, and nerve endings, yet it is not used for seeing. It is visible under young tuataras’ skin but becomes covered with scales and pigment in a few months, making it hard to see. The unique eye is sensitive to light and may help the tuatara judge the time of day or season.