What is the one thing all fossils have in common?

All fossils have in common that they are remains or traces of ancient organisms that have been preserved in some form. They provide evidence of past life and environmental conditions, offering insights into the history of life on Earth. Fossils can be found in various forms, including bones, shells, footprints, and even imprints of soft tissues, but they all share the characteristic of being remnants of living beings that existed long ago.