What you’re looking at is some little rounded rocks and their shadows. They lie on a bed of dust in a little pan on the rocks. I’m not sure how the patterns in the dust formed, I think it may have to do with rain accumulating there as well, and when it dries, it forms these shapes.
I especially like how the light appears to come from the top left, creating the illusion of the little rocks being holes. Actually, the light comes from the lower right, and the rocks cast their shadow to the left.