Provide your best answer for the following question. Give ONLY the answer, no other words or explanation.
For example:

Answer: <most likely answer, as short as possible; not a complete sentence, just the answer!>.

The question is: Paleontologists often find and study the remains of ancient plants and animals. When the remains of ancient plants and animals are covered by layers of sediment over time, the remains
become a fossil
fossilize.