Strange moving stone that can move by itself

We see wonders all around the universe among sky-ground-water. Modern science has been working to solve the mystery behind these wonders. In some subjects, the scientists were able to give explanation. But in several causes of the world cannot be explained by the scientists. Such an event is going to happen on a regular basis at Death Valley of CALIFORNIA, USA. In there are some strange moving stone that Change their position by itself. Although no one watch them to change position but in the mud there has clear evidence of change position. Generally they change their position after two or three years. Some of these stones weight is almost same of a man. It has been observed by the scientist that these stones do not move in a particular path. Sometimes they move straight sometimes zigzag.