I've had my xenia for about a year now and its happily multiplied all over my tank despite poor water quality. I am now much more on top of my water quality. until recently some of it has started to retract while other colonies are better than ever.
are they permanently like that, or just from time to time. My xenia will shrivel up, or contract, every once in a while and then expand back again. They may stay contracted for anywhere from five to thirty minutes and then it was like nothing happened.