Theres some type of thing on my glass. It seems like it may be alive, but I never added anything to my tank, like a tiny slug snail type thing? is this possible? it's a guppy tank and I've had it running since June. I just realized this. Yesterday saw it and tried getting it off with a scrub bad it worked but now it's on another part of the tanks glass.... What is this thing it's about the size of a cotton tip of a q tip and it's brownish.