Trilobites

Trilobites were some of the most successful animals in Earth's history. They lived in the oceans for over 270 million years! That is much longer than dinosaurs existed. Trilobites first appeared about 521 million years ago and are now completely extinct.

Three-Part Body

Trilobites got their name because their bodies had three sections from side to side. They had a hard outer shell that protected them. Most were small, about the size of a coin. But some grew to be over 2 feet long! There were more than 20,000 different species of trilobites.

Amazing Eyes

Many trilobites had some of the first complex eyes in the animal kingdom. Their eyes were made of crystals of a mineral called calcite. Some trilobites had eyes with thousands of tiny lenses. A few species could see in almost every direction at once. Some trilobites had no eyes and lived in dark, deep water.

Fun Facts

• Trilobites had eyes made of actual crystals — the mineral calcite.
• Over 20,000 species of trilobites have been discovered so far.
• Some trilobites could roll into a ball like a pill bug for protection.

Did You Know?

Trilobite fossils are found all over the world and are very popular with fossil collectors. They are so common that you can buy real trilobite fossils at rock shops and science museums!