Small White Dots

[Craster]

Two weeks ago I added a pair of ruby nerite snails to one of my tanks. One of the two had two white markings on his shell - I had assumed them to be natural. These same markings now appear all over a piece of bogwood I have in the tank - I can count about 20 of them. They are circular and barely raised, about 2mm across, and look to all intents and purposes like a small dab of tipp-ex.

Can anyone help to identify them, so I know what (if anything) I need to do about them?

Thanks.

 

[Craster]

Quick bump, as it's already off the bottom of the page.

Thanks.