Fossils that are the actual bodies or body parts of organisms are called original remains fossils. A Mold fossil is a fossil formed when complex parts of an organism are trapped in sediment dissolved away leaving behind a hollow area with the organism's shape. A cast fossil is a fossil formed when sediment fills in the hollow space of the shape of an organism. A carbonized fossil is a fossil when a dead organism is compressed over time and the pressure drives out the liquids and gases leaving behind an outline of the organism
