pulsing xenia ?

[mark]

they will move but if it fallen some place you don't want it, move it back. I'd be balancing out though the effort to pull apart the rock against picking up some more or just leaving alone. Also Xenia can be a bit of a weed. Good chance the remaining piece will split and in a few months you'll be thinking about how to get rid of all the Xenia you have.

If you are going to move it, Xenia are pretty hardy. If it hasn't attached, first try grabbing it with tongs, might even be able to siphon out.