Fossils are the remains or traces of living things preserved in the rocks. In Northern Ireland fossils have been found in sedimentary rocks ranging in age from 500 million years old to a few thousand years old. The Ulster Museum collections contain tens of thousands of fossils, ranging from small fragments of ancient shells to a near complete dinosaur skeleton. Some of the more spectacular fossils are on display. Many other, less exciting, specimens form a valuable scientific resource for geologists.