A15th century farmer finds a rock that looks exactly like a clamshell. what did he likely conclude about how the fossil got there? plz

Fossil is the dead remnants of ancient plants and animals. It takes millions of years to form fossils. The clamshells are the fossils that are generally considered to be the bivalves for the first time during the Cambrian period. They are formed in a shallow marine type of environment and after a definite period of time, the geological processes allow these fossils to expose on the surface. It is due to the erosion of the surface materials.

In addition to this, these fossils that are exposed on the surface are also transported from one place to another because of the agents like water, during flood. The fossils are mostly found along the sides of road cuttings, streams and river valleys and on the sides of the cliffs.

So, according to the given condition, it can be concluded that the farmer found that fossil clamshell because of the rapid erosion that has taken place in that area, exposing the fossil on the surface.