First coral I bought was a Discosoma after reading that it was a great started coral and if you can't keep one of these alive you should find a new hobby. Well, it has been doing poorly while everything else I've got (softies, LPS, SPS) is thriving or at least staying alive.Who'da thunk it! A few days ago I noticed this weird looking bubble like structure growing the piece of rock the Discosoma was mounted on. It appears on two distinct surfaces on the rock. What is it and should I get it out of the tank or let it grow?