I don't understand why you would ask if it is a natural rock. Of course it is a natural rock.

In order to be a carved rock - it would have to be a natural rock.

In fact, it would remain a natural rock, even after the carving takes place.

You seem to suggest it could only be a carved stone column if the substance of the carving was not natural stone.

There are numerous examples on earth, of human beings carving into natural stone. If you are not aware of these, go googling. They often used a hammer and chisel, and other such tools for the task. Believe me, it was not uncommon, particularly before the advent of concrete.

I also don't understand why you think the symetrical points can't be seen. There are thousands of symetrical points in view on both sides of the object. (Simply because there are still points out of view, does not mean you shouldn't consider the numerous points that are in view). In a single view, there will always be points of a 3-dimensional object that can not be seen.

The many symetrical points are there for you to see if you simply look. A few are even labeled. I've noted several for you.

I suggest you pull it up in some good imaging software and zoom in on it so you can see it better. Then study it for awhile before you comment further.