A fossil is the mineralized partial or entire mass of an organism, or of an organism`s body segment, that has been preserved as a cast, impression, or mold.
When residing organisms die and are buried with the aid of using sediments, maximum fossils shape. The sediments regularly harden into rock, retaining the organisms' forms.
Although there are several ways fossils form, most form when animals or plants die in a watery environment and bury them in mud and silt.
Soft tissues break down rapidly, leaving bones and hard shells. Over time, sediment accumulates and hardens into rock.