What is meant by the study of fossils?

When living things die, sometimes they can get buried in mud or sand before they rot away. If this happens, over time the mud or sand can be turned into rock and the hard parts of the living things are also mineralized (turned into rock) but in a way that preserves the structure of the original living thing.

An impression of a living thing preserved in this way is called a fossil and by studying the fossils that are to be found in rocks it is possible to see and understand creatures that lived on earth a very long time ago.