i have some strange things that have appeared in my tank.they look like snails with no shell.i had seen one or two at a time before,but tonight when i got home from work there are litterally hundreds of them.all stuck on the glass.they range from tiny to about a half inch long and maybe a quarter inch wide.the have kind of an oval shaped body that seems to be stuck to the glass,and a tiny head that is stuck as well.i dont know for sure if they are whats doing it,but i have been hearing a popping sound like something hitting the glass.never have seen whats doing it but i'd hear it every now and then during the day.tonight with these things out i am hearing it alot.not positive they are doing it as i havent seen it.i wish i could get a decent pic,but since its dark and the flash reflection blocks out the things on the glass i havent been able to.anybody have any idea what they could be?