Fossil of Phacops rana, a species of trilobite that lived during the middle Devonian period, around 396 to 385 million years ago. Trilobites are a class of marine arthropods, now long extinct, that lived on the sea bottom. This species, Phacops rana (subspecies Africana), is characterized by its large eyes and sizeable body length, up to 15 cm. This specimen was found in limestone in Southern Morocco and measures 12 cm long.