The digestive and muscle systems of trilobites have been studied as well. Sensory antennae have been seen, attached on the underside of the head of the trilobite. In 1994 the first fossilized microscopic trilobite embryos were reported. Like most arthropods, trilobites molted or shed their exoskeleton as they grew. The rocks at the Falls of the Ohio contain common trilobite fragments that are a result of molting.
Complete trilobites are very rare.
One of the largest Devonian trilobite species was found in New York rock layers equivalent to the coral beds at the Falls of the Ohio. Only one has ever been found. Although giant trilobites have not been documented, they probably do occur in the rock layers in the Louisville metropolitan area. The Middle Devonian environment was one of a shallow, wave swept sea floor, teeming with life. The remains of large trilobites would have to buried quickly, or they would have been destroyed by scavengers and ocean currents.