I'm noticing some critters on my rock that resemble what I believe to be flatworms. Now, I have the standard (hopefully) clearish white ones, but these new ones are like dark gray with some white specks on them. I have a great pic on my camera, but my computer has stopped recognizing my camera (go figure). The white guys tend to stay on the glass, while the others seem to never come off my rocks. I guess I'm trying to make sure that these guys aren't going to wipe my tank out.