Maybe this will make it even cooler. Each bubble is a single cell. If I remember correctly, bubble algae is the biggest single cell living thing. I think most people get green bubble algae, but the purple color isn't completely uncommon.
I'd pull the coral out if you can. Carefully pry or peel it off the coral trying not to break the bubbles. If they break, remove the tissue left behind with a tooth brush and then rinse it in a small amount of saltwater from your tank. Then put it back in the tank.