I accidentally got a Forrest Fire Montipora Digitata (I think?) as a frag. It's been sitting at the top of my IM 40 waiting for IM 170 to be ready. I've got Radions running on it. I'm seeing this growth on the bottom of it. Those two "feet" sticking out were not there before. So is it growing/encrusting? What is the proper terminology? I still have it on a frag plug, was waiting to attach to a rock once it was inside 170, but maybe it's time to move it to something more than a plug?
