Sharks are formidable ocean predators armed with rows of razor-sharp teeth. But while living sharks have whitish teeth, fossilized shark teeth are almost always black. So why do these particular shark teeth turn black?
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Shark Tooth Composition
| Tooth Layer | Composition |
|---|---|
| Enamel | Hydroxyapatite crystals |
| Dentine | Hydroxyapatite crystals, collagen fibers |
Shark teeth contain enamel and dentine like other animals. But additional minerals are absorbed during fossilization.
How Fossilization Transforms Color
Shark teeth can become fossilized when they fall out and become buried in sediment on the seafloor. Over long periods, the sediment:
- Pushes minerals like phosphate into the tooth, replacing organic material
- Crystallizes the minerals, turning teeth black through a process called permineralization
- Applies pressure that accelerates the color change
This blackening fossilization process takes at least 10,000 years. Most fossilized shark teeth are hundreds of thousands to millions of years old.
Why Finding Black Teeth Is Common
- Sharks shed over 40,000 teeth in a lifetime
- Mineral-rich sediments like phosphate are excellent for the preservation
- Coastal areas with fossil shark teeth have ideal conditions
Conclusion
Next time you find a black shark tooth, you can be sure it has been transformed by many years of fossilization! The black color is a testament to the tooth’s ancient origin.
