How do most fossils form?

Hint:Fossils are impressions, remains, or traces of prehistoric organisms that are preserved by natural processes. Fossil is not the organism itself. It is the remnant of the organism or part of the body like bones, feathers, leaves, teeth etc.

Complete answer:
 Fossils are solidified remains, traces or trails of plants, animals, insects or any other ancient life forms that are preserved by natural process. Most of the fossils are formed by the process of fossilization. When the body of a dead organism is buried under sand or rock, the soft body part decomposes quickly while the hard parts survive, and the surrounding matter retains the impression of the remaining body parts, thus turning into fossils. This process is termed as fossilization.

These fossils can be large like petrified trees or dinosaur bones or small like bacteria or pollen that are visible only with a microscope. Formation of fossils is not a one day work. It takes around 10,000 years or more to become a fossil. They are found deep down the earth crust. There are two methods of dating a fossil. First, as we dig the earth crust the fossil closer to the surface is the most recent than the fossils found in deeper layers. The second method is by detecting the ratios of different isotope of carbon in the fossil material

Note: Fossils are formed by the process of fossilization. When a dead, decaying matter gets buried in sand, hot mud or rock, the hard parts of the body of the organism that doesn't decompose easily, gets imprinted on the surrounding matter and turns into fossils.