Answer:
High pressure
Preservation.
Step-by-step explanation:
Fossilization is the preservation of the remains of dead plants and animals in a sedimentary rock. When plants and animals are dead in an watery environment, the soft part decayed and the bones or shells remains and this form mold in sedimentary rocks.
High pressure help the bones , shells or remains of plants and animals to mineralize or undergo mineralization.
Preservation is when the remains are protected from oxygen to avoid corrosion and been eroded. There must also be an hard parts from fossilization to take place.