I agree with mel,
LR (at least the way it is meant) indicates the presence of nitrifiying bacteria. If you are wondering if there is life on the rock, check the colors, and there should be some worms or "
pods" when you lift it up, also, you might see some algae or feather dusters.....If the rock looks bleached, then it is probably just base rock. From your pic, it looks like there is some coraline there (maybe a little purple...)?