No archaeologist is an expert on the antiquity of all regions of the world and all time periods. Classical archaeologists concentrate on the ancient civilizations of the Middle East and the Mediterranean world (Egypt, Mesopotamia, Greece, Rome, and related peoples). Historical archaeologists work on recovering the unrecorded aspects of life in historically more modern societies such as colonial America. Prehistoric archaeologists focus their attention on the more ancient pre-literate societies around the world including those of most early North American Indians. Underwater archaeologists discover and excavate ancient shipwrecks and submerged cities. Zooarchaeologists analyze and interpret the animal remains found in archaeological sites. The training required for each of these and other archeological specialties varies significantly, but they all share an interest in elucidating the lost past.