What are the typical conditions necessary for fossii formation?

Because most geological processes involve erosion more than deposition—that is, things are taken away rather than piled on—fossil formation rarely occurs on land.

The majority of fossils are formed in the ocean, where they are deposited on the ocean floor.

Furthermore, since the body must leave a strong imprint on the rock, decomposition would weaken the structure of the imprint. Since oxygen is the primary catalyst for decomposition and water is mostly oxygen, once an organism is dead, it is covered in a layer of fine mud that prevents water from easily penetrating it. Since water moves through sand very quickly, it is also ineffective for fossilization.

Following mud cover, the organism is burdened by layers of sediment that accumulate over millions of years. The organism's imprint is preserved as a fossil by the pressure and heat that form sedimentary rock.

Because certain species—like jellyfish—have no chance of going without oxygen or lack hard skeletons to leave an imprint, they are largely absent from the fossil record, according to paleontologists, who believe that the record is biased.

Volcanic ash is a suitable material for fossilization on land because it is fine and can capture minute details, whereas coarse gravels are less flexible.

Maintaining a steady temperature also prevents thermal disruption during fossilization.

The typical conditions necessary for fossil formation include rapid burial, anaerobic (low oxygen) conditions, minimal disturbance, and the presence of sediment or other materials conducive to preservation, such as mud, silt, or volcanic ash.