Scientists have come to know about such an animal of the Arthropod group, which used to have three eyes. After studying fossils that are 500 million years old, a lot has been known about this animal.

A three-eyed animal with wing-like fins once swam through shallow seas, using heightened visual perception to hunt smaller sea animals.

Stanleycaris hirpex lived in the Cambrian Period about 500 million years ago, not long after the first eyes appeared in the fossil record. It is the first animal with three eyes known among the arthropods, the group containing insects, arachnids and crustaceans, but the researchers who described it think there may be others in which a third eye has been overlooked.

S. hirpex was roughly the size of a human hand and had two protruding eyes with hundreds of lenses on each side of its head, plus a third, much larger eye in the middle.

According to research published in Current Biology,  in many of the 268 samples, soft tissue was still intact. Moyciuk says that even after 506 million years, the fossilized rock can be seen with its eyes shining in the sun. So it was very clear that it had three eyes. This animal had 17 body segments, with two pairs of hard blades along the lower part of its body. Its claws were pointed, which suggests that it was a ferocious hunter.