Dirt and shadow.
Plus what are known as "artifacts", from the resolution.
The pixels (the data used to create such images) tend to distort all detail below a certain size. If there are a couple of objects side-by-side that are each about a pixel wide, then the image might show them as one large object, and so on. Pretty much the same as for the whole 'Face On Mars' and/or 'Aliens On The Moon' thing.
Plus plus, go through enough pics of any fairly randomzied landscape (on Earth or elsewhere - any magnification) and you will soon find lots of weird things - Smiley Faces, Jesus On A Tortilla Chip, whatever.
These things can be very entertaining to find, but I''l bet that in any/all pics of different resolution, taken from different angles and lighting, it will look quite different.