Yeh I took two rocks out and brushed them off... But they are everywhere! Glass, sand, rock. Pretty much everything in lower half of tank is covered....cleaned them off and were back with a couple weeks.....when I previously asked about this, someone asked if I can pop them (so if they were like A bubble algae) but I cant..Cant you just take the rock out and take them off ? What do you mean its not pop able, it is not part of the rock so has to come off. Looks like some kind of a shell fish l but cant say I have ever seen so many together