Trace fossils record the behaviors of ancient animals in sedimentary rocks. They are not parts of individual animals, but rather evidence of their activity. Comparing these fossil records with behavior of modern animals helps to build a clearer picture of the biology of the animals that left them behind. Trace fossils include burrows, trackways, trails and borings. The specific maker of these fossils is often difficult or sometimes impossible to know. When the animal that left a trace fossil behind is identified, the information it provides can be very enlightening. Trace fossils reflect movement, bringing the ancient world to life.