Trilobites are a well-known fossil group of extinct marine arthropods, one of the earliest known groups of arthropods. They first appeared in the fossil record in the Early Cambrian Period (526 million years ago), and flourished throughout the lower Paleozoic Era before beginning a drawn-out decline to extinction when, during the Devonian Period, almost all trilobite orders died out before finally disappearing in the mass extinction at the end of the Permian Period, about 250 million years ago. Trilobites were among the most successful of all life forms, roaming the oceans for over 270 million years. Offered here is a complete fossilized example of Phacops rana, measuring nearly 3" wide and 5.5" long. This fossil dates to the Devonian Period (419.2–358.9 million years ago) and was unearthed in Morocco. The most striking feature of the morphology of Phacops rana and its relatives is their eyes. These differed from the eyes of most trilobites in having comparatively few lenses spaced between deep sclera. The lenses themselves were very rounded instead of largely flat. The eyes were mounted on turret-like structures which could swivel, providing the animal with an almost 360 degree field of view. This trilobite's right eye is remarkably well preserved, w/an amazing amount of detail visible. These trilobites are often found rolled up in a ball-like position, a defensive feature they used to protect themselves from predators, w/its hard exoskeleton on the outside acting like a shield. This specimen is fully stretched out, and wonderfully preserved. From the Robert M. Overstreet Collection and comes with COA.