Trilobites are a group of extinct marine arthropods that first appeared around 521 million years ago, shortly after the beginning of the Cambrian period, living through the majority of the Palaeozoic Era, for nearly 300 million years.
These little guys are approximately 1/4"-1/2" in length, and all complete fossils. The fossils come attached to the limestone they were discovered in. They each come in a box with an information card.