Clean the tank today did a 10% water change, and this was not there. About 5 hours later, black gel like with what look like little worms. nothing been added to the tank in weeks ,last iteam added was 5 turbo snails about 3 weeks ago. check leval and everything was in check. Is it some type of algea and if so what the best way to get rid of it? Thanks for any help on this matter. Sorry the pics are not the best.