This is close up photo of road salt in an asphalt parking lot. The motion implied by both the highlights and shadows seems to result from the physical process of dissolution as well as the nature of how objects in motion along a surface seek a path of least resistance.
As a side note, I was running errands and wasn’t planning on taking any pictures. On my way into the store, I looked down and saw this image. I turned around, went back to my car to get my camera (which I always keep in the trunk) and started shooting.