Description: This is a fine example of an Ordovician Moroccan trilobite known as Cyclopyge. Notice the placement of the enormous eyes at the side of the cephalon. The trilobite is thought to have been mesopelagic, meaning that it lived in the depths of some 200 meters. They slowly moved along filtering plankton. They lived in the dim twilight zone, and so needed large eyes to gather in light. Studies have shown their eyes to be similar to those of modern insects and crustaceans that live in dim light. Notice the exceptionally well-preserved eye facets. Interestingly, some of these deep-water pelagic tributes possessed square rather than hexagonal lenses for reasons as yet unknown.