The traces and remains of ancient lifeforms are called fossils. The study of fossils is called palaeontology. Studying of fossils helps us to understand the evolution of environment and natural communities. Fossils are preserved in different ways. They are fossilized through amber, ammonites, volcanic ash, petrification etc. Corals are the most popular fossils. They have hard skeleton. Soft-bodied animals such as jelly-fish and sea anemone would have lived in the same community. Fossils range from microscopic animals and plants to huge bones of dinosaurs.
Amber: The fossilized resin of gymnosperms called amber often contains bodies of insects and other small animals and plants.
The above image is a 15-20 years old stingless old bee preserved in amber. The stuff on its back are pollinia and represent the only known piece of fossilized orchid ever discovered.
Ammonites: They are mollusics which were in the seas of Mesozoic era. Their shells were made from the mineral aragonite
Volcanic ash: It is very rare type of fossilization. When the volcanoes spreads, the ash turns the body of the animal or plant into a rock quickly. Buried animals or plants may rot away to leave a hollow.
Petrification: It is also a rare type fossilization. This happens when silica-rich water crystallizes within the cell of the cones.
Fossil Dating: Some fossils such as graptolites and conodonts evolved and become extinct over a short period of time. This makes them useful for dating the rock in which they are formed.