trilobite

Any of numerous extinct marine arthropods of the class Trilobita, of the Paleozoic Era, having a segmented body divided by grooves into three longitudinal lobes and found as fossils throughout the world.

Any member of the Trilobita: so called from the three lobes or main divisions of the body—cephalic, thoracic, and abdominal. See Trilobita.

Any one of numerous species of extinct arthropods belonging to the order Trilobita. Trilobites were very common in the Silurian and Devonian periods, but became extinct at the close of the Paleozoic. So named from the three lobes usually seen on each segment.

An extinct arthropod of the class Trilobita, whose body had three large lobes.

an extinct arthropod that was abundant in Paleozoic times; had an exoskeleton divided into three parts