TRILOBITE

Trilobites are incredibly diverse and long extinct arthropods that are characterized by a three-lobed, segmented exoskeleton and the ability to molt. They are considered the very distant relatives of modern lobsters, horseshoe crabs, and spiders, and ranged in size from a third of an inch to roughly 30 inches in length. These prehistoric critters spent their entire lives roaming the sea floor and coral reefs in search of food, with certain species of the trilobite family using incredibly advanced calcite crystalline eyes to hunt for smaller marine prey! These crystal eyes allowed them to navigate, find food, and spot predators across diverse marine habitats, from the sea floor to the open oceans. They were among the first animals to develop these complex eyes, giving them a major advantage when hunting for food. Trilobites evolved into over 20,000 different species and lived from the Lower Cambrian Period (521 million years ago) to the end of the Permian Period (250 million years ago) before going extinct in the Permian-Triassic mass extinction event. "The Great Dying," occurred approximately 252 million years ago, marking the most severe extinction in Earth's history. It wiped out roughly 90–96% of marine species and 70% of terrestrial vertebrate species.