A fossil is the preserved remains or traces of ancient organisms, typically found in sedimentary rock. Fossils can include bones, shells, and even imprints of plants or footprints. They provide valuable information about the history of life on Earth and how species have evolved over millions of years. The process of fossilization usually occurs when an organism is buried quickly after death, protecting it from decay. Over time, minerals in the surrounding sediment replace the organic material, creating a fossil. Fossils are crucial for scientists, including paleontologists, who study them to understand past ecosystems and the evolution of life, including species like dinosaurs.