Bubble coral need to be in a very dim shaded spot with low flow. They also need to be fed a few times a week to thrive. Form follows function so the bubbles are there to increase surface area for their symbiotic algae to capture light. They are a very active feeding coral at night so I believe they get alot of their nutrition through hunting rather than photosynthesis. The bubbles don't do well in high flow or medium flow as they tear on the skeleton. Good luck
Don't mean to disagree. But watch this please..
Green bubble coral: http://youtu.be/tSxtCx9v7L0