Yes, tube like branches. I don't know much about galaxea but I thought they had larger polyps. I had thought it might be a type of pociliopora but I don't know...
tall-90 - The sun coral opens up for cyclopeeze. I wouldn't put it in a cave if I was you, put it one the sand somewhere you can cover it, then put a little cyclopeeze in the tank, wait for it to open, then cover it and shoot a lot of cyclopeeze or whatever food you're feeding under the cover so it can eat.