When i recently put in some java moss in my tank, i saw a single snail. I have no idea what kind it is, except that my googlage has shown it most similar to the Physa snail. which, if it is, makes me a bit sad, because aquaguide says those snails do nothing about algae. any ides on what other common snail it might be? it had a dark brown shell with whitish flesh. i haven't seen it ever since that one time and i don't think i'm going to dig around my gravel to find it.