Here's how it works:
* The organism is buried: An animal or plant dies and gets covered by layers of sediment (like sand, mud, or volcanic ash).
* The organism decays: Over time, the soft parts of the organism decompose.
* The sediment hardens: The sediment around the organism compacts and hardens into rock.
* The organism dissolves: The remaining hard parts, like bones or shells, are dissolved by groundwater or chemical reactions.
* A hollow space is left: The space where the organism was is now an empty mold.
Sometimes, minerals from the surrounding rock fill this hollow space, creating a cast, which is a replica of the original organism.
So, while a fossil is a preserved remnant or trace of an ancient organism, a mold is a specific type of fossil that is the impression left behind by the organism.
