The Calymenina (“KAH-lee-meh-NEE-nah”) suborder of these animals is characterized by having its suture end at the genal (“jee-nal”) angle. A set of structures found in these animals can be classified into holochroal (“HOE-loe-krole”), schizochroal (“SKIT-soe-krole”), or abathochroal (“ah-BAH-thoe-krole”) subtypes. In 1999, a research group from the University of Manitoba discovered the largest one of these animals near Churchill measuring at 28 inches long; that animal is of the species Isotelus (“EYE-soe-tehl-uhs”) rex. These animals, which were the first to have evolved (*) compound eyes, proliferated by the end of the Terreneuvian (“TAYR-uh-NOO-vee-an”) series of the Cambrian era. Due to their similar appearance, horseshoe crabs (10[2])are often erroneously stated (-5[1])to be the closest (10[1])relative to these invertebrates. For 10 points, name these extinct marine arthropods named for their “three-lobed” body organization. ■END■ (10[1])