"Well, bioluminescence, the only thing I can think of, is quite possible. However, this would be if it was a fungus or a lichen for plants, or a mass of bacteria on it. In this hypothetical situation you speak of, would there be a chance of a plant on it? If all you see is light, it would probably be bacteria. That is, if scientific laws are still in place. Everything seems to be changing rather quickly lately, so I cannot be too sure. Other than that, it can always have had glow in the dark fluid poured on it."