multiple white dot's on glass and rock

[aquablizz]

any forum members have an idea of what is causing this problem.. They are becoming very noticeable and are hard to scrap off. not much bigger then a pin head.. even growing on top of the coralline algae in both the display tank and fuge.. when I say multiple, I mean hundreds and appear to be getting worse

blizz

 

[jmerideth1]

Hard too see in the pic but if there is a spiral shape too them they could be a small kind of feather duster.

 

[Mikedawg]

Probably spirorbid worms; I use a razor blade scraper or a credit card to get them off, particularly the empty shells. Believe they feed on detritus so water conditions influence their growth.

 

[aquablizz]

Thanks for getting back to me... looking at them with a magnifying glass they do appear to be a tiny circle.
Is there anything that can be done to stop their growth?? My water parameter is very good with undetectable numbers in both phos and nitrate.

blizz