Fossils are our only clues to life in the past.
They help us learn about evolution - how living things have changed through time. Fossils are like a photograph of an animal at a particular point in the history of the Earth. Fossils also help us understand what kinds of environments existed millions of year ago. For example, by studying fossils, paleontologists have learned that 440 million years ago, Ontario was covered by a warm, shallow tropical sea full of corals, trilobites, sea lilies, clams, and other creatures. Some ancient animals, such as trilobites, have no close living relatives.