The remained parts and elements of an organism that live several years ago is called as fossils.
Due to natural processes like weathering, soil erosion and other geological activities fossils are hard to preserve.
Carbonization, permineralization, recrystallization and replacement are the fossil formation processes.
Carbonization is the chemical reaction forming the thin film of carbon of the organic material.
Permineralization includes the fossils of bones and teeth. The recrystallization process is responsible for changing the micro-structure of the organic materials to form the fossils.
