White donut shaped thingy's

[Noj]

Hey everyone

I tried to take a picture of the above named things, but the pictures just dont turn out. The things I am refering to are very small, attached to the back glass and look like tiny white donutes. They are about the size of a few grains of sand or salt.

I have nothing but live rock and snails in my tank and it has been up and running since the first week of March.

Thanks

-Cam