What are fossils? How are most fossils formed?

Fossils of hard mineral parts (like bones and teeth) were formed as follows: Some animals were quickly buried after their death by sinking in mud, being buried in a sand storm. Over time, more and more sediment covered the remains.

"Fossils of hard mineral parts (like bones and teeth). Fossils of hard mineral parts (like bones and teeth) Fossils are formed in a number of different ways, but most are formed when a plant or animal dies in a watery environment and is buried in mud and silt. Soft tissues quickly decompose leaving the hard bones or shells behind. Over time sediment builds over the top and hardens into rock."