These rocks are nothing more than rocks everywhere. Mercury’s got rocks, Venus has rocks, just as every planet, moon, asteroid, and comet. Likely, Jupiter and the others have rocks deep down. Rocks likely pervade the universe on bodies cool enough to be solid. There is no evidence that these are anything but rocks. Perhaps wind and weathering have moved some smaller ones, and when the sand shifts, the larger ones may appear to have moved. But, they are still just rocks. If new evidence is discovered, that could indicate some possibilities, but, the existing evidence indicates that they are what they look like . . . Rocks.