Step 1: Understanding the Concept:
When organisms die, they usually decompose completely. However, under specific geological conditions, their remains can be preserved.
Step 2: Detailed Explanation:
Fossils are the naturally preserved physical evidence of past life, typically found embedded in sedimentary rocks.
They can include hard parts like bones, teeth, and shells, or even impressions like footprints or leaf prints.
Step 3: Final Answer:
A fossil is any preserved evidence of life from a past geological age.