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How does a fossil form?
Quick answer
A fossil forms when the remains or traces of a once-living thing are preserved in rock over thousands to millions of years. Usually, minerals slowly replace buried bone or shell, turning it to stone and capturing a record of ancient life.
Step by step
- An organism is buried quickly by sediment after death.
- Soft parts usually decay; hard parts like bone remain.
- Over ages, minerals seep in and replace the original material.
- The remains turn to rock, preserving their shape.
- Fossils reveal the history of life and help date rock layers.
People also ask
How does a fossil form?
Remains get buried in sediment, and over long ages minerals gradually replace the hard parts, turning them to stone while keeping their shape.
Why are fossils usually bones and shells?
Soft tissues decay quickly; hard parts like bones, teeth, and shells last long enough to be mineralized and preserved.
How do scientists know a fossil's age?
By dating the surrounding rock layers and using radioactive decay (radiometric dating) to estimate how long ago it formed.
Part of the guide: Nature & Earth: Living Things and Rocks →