Fossils
fossils: An animal that has been dead for many years and that type of animal is extinct
-the level of rock they're on determines how long they have been dead
-when the animal dies, over time they get covered with dirt, rock, or even sand and that is how they become a fossil.
-if two types of animals are in the same level of rock that shows that they both died almost at the same time.
the image below shows a fish that has died and over time, became a fossil.