What are fossils ? How do they form ? Give example of various kind of fossils ? How do we know how old the fossils are ?

Explanation

The fossils are the remains or impressions of the dead animals and plants that lived in the past.
Usually, when organisms die, their bodies are decomposed and lost. However if the body or some of its parts remain in an environment that does not let it decompose completely, the body or its parts will eventually be preserved or alternately leave the impressions.
If a dead insect gets caught in mud, it will not decompose quickly, and the mud will eventually harden and retain the impression of the body parts of the insect.
There are two methods to estimate the age of a fossil.
(1) Relative method : This method depends on the depth at which fossil is found. If we dig the earth to locate fossils, the fossils we find closer to the surface are more recent than the fossils we find in deeper layers.
(2) Carbon dating method : The dating of rocks or fossils is done by working out the ratio of different isotopes mainly `C^(14)` of the same element in the fossil material.