Fossil trilobites are quite common.

Even though they are now extinct, there were more than 10,000 different trilobite species that crawled along the sea bed or swam through the water.

This fossil trilobite is unusual because it is curled up.

This behavior is common in some living animals.

For example, certain pill bugs curl up to protect themselves.

By comparing the fossil trilobite to animals like pill bugs, paleontologists can infer that trilobites rolled up for protection from predators.