Mental Floss has a post about trilobites.  Here are some highlights.

• Over 20,000 species are currently known.
• Trilobites first appeared around 450 million years ago.
• Many would curl up into little balls for protection.
• At first, scientists didn’t know what to make of them.
• Most trilobite fossils are actually molted exoskeletons.
• Three states have made a trilobite their official fossil.
• Trilobites gathered food in a variety of ways.
• Trilobites were wiped out by the biggest extinction in history.
• Native Americans used them as amulets.
• One Chinese trilobite was named after a Star Wars character.

Check out the details here!