Something new in my tank...

[kari]

Can't tell you what they are but I am pretty sure they are the same thing I have been staring at for years. White in color, roundish, rather flat, like to hang out on the glass and move very slowly. They are crushed with a magnetic glass scraper pass and the fish love to eat them as the scrapper goes by. I haven't seen any harm done by them. Free food for the fish.
If they are the same thing, they are definately not Cerith snails or their eggs. Maybe some other type of snail or limpet type critter is my best guess.
Try posting a pic as my camera is useless.