Fossils are preserved remains of ancient plants and animals. Fossils can be bones, footprints, or plant imprints! Fossils only form under the right conditions, so that makes them a rare find. Fossils are start with a dead plant or animal. Over time, the plant or animal gets buried under layers of sediment and rock. That creates lots of pressure and heat. That pressure and heat decomposes the soft parts of the plant or animal, laving only the bony or woody structure. Then, minerals from water seep into the bone or remain of a plant and start to deposit minerals. Over time, you get a solid imprint of the bone, footprint, or plant!