Form when minerals replace all or part of an organism, turning it into rock A fossil of the delicate remains of an organism, such as the leaves of a plant. These two kinds of fossils are opposites of one another. These can be created when an animal walked in mud long ago and then the mud hardened into rock. These fossils show the activities of organisms. These fossils include a hollow in the shape of the organism. These fossils contain the actual plant or animal that was preserved. These fossils form when all of the materials that make up an organism break down and only carbon remains. Scientists used these types of fossils to study animal behavior (how they moved, etc.) These fossils form when an organism becomes trapped in a tree sap, tar, or ice. These fossils look like a picture or negative of an organism. Contain the actual remains of an organism. Sometimes even the hair is preserved!! These fossils show a 3 dimensional form of the animal sticking out from the rock. These fossils fit together like puzzle pieces.