Fossils can take millions of years to form. The process is incredibly slow and depends on several factors.
- Death: An organism dies in an environment where it's unlikely to decompose quickly, like deep water or buried under sediment.
- Covering: The remains are rapidly covered by layers of sediment, protecting them from decay and erosion.
- Petrification: Minerals replace the organic material over time, turning it into stone. This can take thousands to millions of years.
Pro tip: Fossils found in younger rock layers are usually more recent than those in older layers, but exact ages vary widely.