Book 32, Question 107
Why do tuataras and some lizards have a “third eye”?
On top of a tuatara’s head, there is a small spot that works like a third eye.
It is called the parietal eye, and it is covered by skin and scales. It can’t see pictures, but it can sense light and dark. It may help the animal keep track of the time of day or the seasons. Many lizards have a parietal eye, too.