About hundreds of millions of years ago, fish lived in rivers, lakes and oceans. After death, the fish sank to the bottom of the water and was covered by deposited sediment. Because the air at the bottom of the water is isolated and covered with sediment, the fish's body will not rot. ?
After hundreds of millions of years of changes, it has been isolated from the air for a long time and has also been affected by high temperature and high pressure. The sediment covered on the body is getting thicker and thicker, and the pressure is getting bigger and bigger.
The bodies of fish caught in these sedimentary rocks have also become stone-like and very hard, which is the so-called "fish fossils".
Extended data
Form the necessary conditions:
1, organic matter must have hard parts, such as shells, bones, teeth or woody tissues. However, even very fragile organisms, such as insects or jellyfish, can become fossils under very favorable conditions.
Living things must avoid being destroyed immediately after death. If the body parts of an organism are crushed, rotted or severely weathered, it may change or cancel the possibility of this organism becoming a fossil.
3. Buried biological corpses must undergo long-term chemical fossilization to form fossils.
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