I'm not sure, but I think am3gross misunderstood, and thinks you're talking about bubble algae. Because he said have a emerald crab eat it up. :notsure: I don't think it is bad for air bubbles to be on the rock. If you are talking about bubble algae, then am3 is right.
If ur tank is just set up u might be talking about oxygen bubbles on ur rock and that is normal for a new tank set up when it goes thourgh the algea stages, when i set mine up i had the same thing but they will go away as the tank matures.