Mine was sold as a white xenia, could be the same Xenia umbellata:

You can see on this photo, how it moves from rock to rock - elongates, touches, attaches, disconnects.
I would think, that placing it on a removable pieces of rock is preferable, this way the excessive growth can be removed together with LR rubble.
Mine didn't hurt anything (but I kept it away from candycane just in case), but was hurt by hammer coral.
GARF keeps xenia bed for the nutrient export for SPS tank, with the skimmer after xenia.
Xenia should produce terpenoid compounds, but I hadn't any problems even in non-skimmed tanks.
Really nice coral.