If you’ve ever visited the fossil gallery of a natural history museum—or its gift shop, for that matter—you’ve probably seen the armored body remains (or exoskeletons) of an extinct group of animals called trilobites. These ancient marine arthropods lived in the world’s oceans from 521 million to 252 million years ago. If you’ve ever visited the fossil gallery of a natural history museum—or its gift shop, for that matter—you’ve probably seen the armored body remains (or exoskeletons) of an extinct group of animals called trilobites. These ancient marine arthropods lived in the world’s oceans from 521 million to 252 million years ago. Paleontology & Fossils Phys.org – latest science and technology news stories