If anyone can tell me what the white mass is growing on the stem of this torch I would appreciate it. It has been on there ever since I bought it about a year ago. Problem is it is starting to reach the heads and I am worried it will kill the heads. It is not a sponge as it is hard and slimy to the touch. There are several holes in it making me think it is some sort of filter feeder. Also wondering if it will spread as I don't want it anywhere else in the tank. I have removed most of it at least once but it grows back fairly quickly.