I can not say, please let us know if it goes down. There is a disease or infection that cause LPS to over inflate like a ballon. It usually goes down but the infection usually causes death. I had a trachy that had it but it was the whole coral not just a bubble.
What are you referring to? If the sponges i see a yellow and a larger one. They are harmless. The will grow where ever it is less light. They filter the water.