the fossilization process starts off with when some animals it was quickly buried after its death (sinking in mud, buried in sandstorm). over time more sediment comes and covers more. After a long time, the chemicals in the buried animals' bodies underwent a series of changes. As the bone slowly decayed, water infused with minerals seeped into the bone and replaced the chemicals in the bone with rock-like minerals. The process of fossilization involves the dissolving and replacement of the original minerals in the object with other minerals. This process results in a heavy, rock-like copy of the original object - a fossil