Fossils can provide clues to how crops and animals lived up to now – what they appeared like, what they ate, what environments they lived in, and the way they advanced and went extinct. For lots of of tens of millions of years, the remains of organisms (as well as tracks, trails, and burrows – called trace fossils) were nearly all of the clues left behind in Earth’s fossil record. A fossil may be studied to determine what sort of organism it dig this represents, how the organism lived, and the method it was preserved.