I saw something in my tank tonight and had noticed its actions before but couldn't find the culprit.
It is very small and snail-like but is spitting out what looks like smoke in intervals of 10 or so at a time and then retreats back into its rock.
Right now it is the size of a large toenail (sorry for the awkward description)
Any ideas, anyone ever seen this, is this bad?
What should I do?