trilobite

A trilobite is an extinct marine arthropod that lived roughly 520 to 250 million years ago. Recognizable by its segmented body, which was divided into a head (cephalon), a segmented thorax, and a tail (pygidium), it had a hard exoskeleton for protection. Trilobites were among the earliest known groups of complex animals with eyes, and they thrived in ocean environments. Their fossils are important to scientists because they help date rock layers and understand early marine ecosystems. Despite going extinct long ago, trilobites are considered some of the most well-preserved and diverse fossils from the Paleozoic era.