Their eyes weren't the only things that varied between different Trilobites. They also lived in different areas. Most Trilobites lived in the shallow water that surrounds continents. While some were swimmers and floaters, most just laid at the bottom of the water. These bottom-dwellers are thought to have eaten bacteria that used sulfur for energy. It has been proposed that the bacteria lived on the bottom of the thorax and on their legs. Another interesting fact about this type of Trilobite is that the babies are thought to have lived in a pouch on their mother until they could collect their own bacteria. Trilobites with very bad eyes seemed to have preffered to live in the deeper darker water and some even went underground to find food and protection. Another means of protection was tyo roll into a ball like an armadillo, onnly allowing their exoskeleton to show. Because Trilobites lived throughout the oceans of the world and they evolved quickly, geologists are able to use their fossils to assist in dating rocks.