For example, if a field is planted with wheat, the wheat is fluttering in a circle in the same direction. Such a round shape is called a circle in English. The reason why the word "mystery" is added to the word "circle" is because these round shapes in the field mysteriously appear all of a sudden at some point in time. We do not even know if they were created by nature or by someone else. This is indeed a mystery. That is why they are mysteries.
After that, many crop circles were discovered. Some people started saying, "This could be the aftermath of a UFO landing," and there was a great deal of excitement. Some people even claimed that a mischievous person had secretly made them.
Recently, however, it is believed that this is caused by a type of electricity called plasma. It seems somewhat strange that electricity can occur unintentionally in nature. However, lightning is also electricity. It is not at all strange that electricity occurs in nature.
However, there are still many things we do not know about crop circles. They are still a mystery. However, as research continues, we will gradually learn more and more about them.