Let’s briefly talk about how fish fossils are formed.

After hundreds of millions of years of changes, the fish carcasses are covered with thicker and thicker sediments. The fish carcasses sandwiched in these sedimentary rocks are "fish fossils".

About hundreds of millions of years ago, fish lived in rivers, lakes and seas. After the fish dies, it sinks to the bottom and is covered with sediment. Because the air at the bottom of the water is isolated and covered with sand, the fish carcasses will not rot. ?

After hundreds of millions of years of changes, long-term isolation from the air, and the effects of high temperature and high pressure, the sediment covering the corpse became thicker and thicker, and the pressure increased.

The fish carcasses sandwiched in these sedimentary rocks have also turned into stone-like things and are very hard. These are "fish fossils".

Extended information

Necessary conditions for formation:

1. Organic matter must have hard parts, such as shells, bones, teeth or woody tissue. However, under very favorable conditions, even very fragile organisms such as insects or jellyfish can become fossilized.

2. Creatures must avoid destruction immediately after death. If an organism's body parts are crushed, decayed, or severely weathered, this may change or eliminate the possibility of that organism becoming a fossil.

3. The buried biological corpses must undergo a long period of petrification before they can form fossils.

Baidu Encyclopedia-Fish Fossils