Question

What parts of an organism become a fossil?

Answer 1

Usually only the hard parts become fossilized

Explanation:

The soft parts are sometimes preserved as fossils mainly as molds and casts. More often the soft parts disintegrate before a record of them is recorded in the sedimentary layers.

The hard parts take longer to disintegrate and have a much better chance of being preserved. Often the hard parts like bone are gradually replaced molecule by molecule with stone.

However in the right conditions even footprints have been preserved by being covered quickly with mud.