I don't think there bad. But I was wondering what they can be. They are tiny little clear sacks with a little white dot in the middle. I have seen them on other peoples tanks but know one ever knew what they were, and I would like to know what they are. Next time I get some on the glass I will try and get a good pic. I will wipe them off and they will return. They'll go away for a while then return for a couple weeks.