A fossil may represent only one part of the organism, or it may preserve the majority of that organism's anatomy.
Most fossils consist of hard body parts such as shells, teeth and bones.
These body parts have the best chance of surviving in the rock record because they are the most resistant to weathering. Other types of fossils, known as trace fossils, preserve the activities of some of these less represented soft-bodied forms. Some animal tracks, trails and burrows made over 400 million years ago are similar to those made by modern animals, such as marine worms and jellyfish, and allow us to infer their presence in the geological past, even if their bodies have not been preserved. Every fossil has a tale to tell about past life and the world in which it lived. Each fossil represents an organism that was once part of a living community, surviving in an environment that at times resembled our own present day settings, and at other times would have been very foreign to us.