Found this type of bubble growing on my galaxea frag. Nowhere else in the tank. The bubbles were full of (water?) I hope. And they were attached to the coral. They would not pull off i had to scrape them off. Then the coral recieved another coral dip then a saltwater rinse. Now back in the tank. But not sure if it was a type of bubble algae. Some pictures. One of the bubbles had baby bubbles but the baby bubbles were not attached. They came off easily.