# Fossil

The preserved remains or traces of a living thing from long ago, often found in rock.

Biology (school) · Part 06: Variation and evolution · Card 7 of 11 · Last updated 2026-10-19

## Analogy

A footprint in cement that stays after the walker has gone.

## In practice

Fossils show how animals like horses changed over millions of years.

## Practice

### Flashcards

- **Why are fossils useful?** They show what past life looked like and how species have changed.

### Interview questions

**What evidence supports evolution?**

- Fossils show gradual change over time
- Antibiotic-resistant bacteria evolve quickly
- Similar DNA in related species
- Extinct species found only in older rock layers

## Questions people ask

### How are fossils formed?

Most fossils form when hard parts such as bones or shells are buried in sediment and slowly replaced by minerals. Others are preserved in amber, ice or peat where decay cannot happen. Some are traces like footprints. Few organisms become fossils, so the fossil record is incomplete.

### Why is the fossil record incomplete?

Most dead organisms are eaten or rot away before they can fossilise. Soft-bodied creatures rarely leave remains. Many fossils may have been destroyed by geological activity, and many have not yet been found. This is why we still have gaps in the story of how life changed.

## Related concepts

- [Evolution](https://studyvisually.com/learn/science/biology-school/biology-school-part-6/biology-school-part-6-concept-5)
- [Extinction](https://studyvisually.com/learn/science/biology-school/biology-school-part-6/biology-school-part-6-concept-8)

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