Strange looking Xenia?

I bought a piece of xenia about 5 months ago, it sat on a rock and didnt do much. A few months later it branched and bolted to a rock, then split. This has happened again recently. I now have 3 pieces (Pic 2 red x's). One piece has started to go quite thin, and looks like it is going to seperate in more than one place, not just split like normal. It also looks a bit different, more transparent if anything, and looks like it is trying to climb up the rock as it splits. I have also noticed single polyps apearing on the live rock, and this morning in the sand. Does it drop of and re grow as well as split? And would the colour change be down to it getting to close to green star polyps or zoas?
I have also noticed a lot less sludge in the skimmer recently, maybee I need to turn it up.

 

It looks like silver xenia, but the stem is to thin from the ones I have seen, I Know that they will propagate quickly in some tanks and fail to thrive in others even if all the water/ light condition seem to be the same. I cant explain the color chang either, Anyone?

 

Yep,that's how they spread from rock to rock,the stem will attach where it's touching then grow thin and finally seperate,starting a new colony.Don't know about the color,have you added any supplements lately that might cause it? BTW,I was able to keep mine from spreading too far by placing my frogspawn uphill from it which stings it back keeping it in check.It tends to spread upward towards the light.

 

No the colour was always a pale silver grey colour, its just gone lighter in the last week. maybee just because its growing up the rock. Usually just one piece touches something and then splits, but this time the whole coral is up against a rock, and its splitting all over. Also noticed some polyps in the sand, and some growing on rocks. No stems, just heads.