Each eye is about the same volume as the animal's brain. An ancient tower-eyed trilobite with dozens of calcite lenses. Trilobites evolved a wide variety of eye forms. Trilobites lived between 521 and ...

The eyes of some trilobites contained more than 15,000 calcite lenses; they looked through crystal at a world of fragmented light. Some had a field of view that was almost 360 degrees. Others ...

They have 24 eyes arranged in four clusters; 16 are simply light-sensitive pits, but one pair in each cluster is complex, with a sophisticated lens, retina, iris and cornea. Trilobites went down a ...