Fossils are the preserved remains or traces of ancient living organisms, such as plants and animals. They can be found in various forms, including bones, shells, and imprints in rocks. Fossils provide valuable information about the history of life on Earth and how different species have evolved over time. The process of fossilization usually occurs when an organism is buried quickly after death, protecting it from decay. Over millions of years, minerals in the surrounding sediment can replace the organic material, turning it into rock. This process helps scientists study past environments and understand the changes that have occurred in Earth's history.