Id small crustacen like creatures growing everywhere

[vipvenom]

Hi,
I have these small tube like structures growing in my tank. They are spreading, even to the glass. When I scrape them off they are very hard and don't come off easily. They are spreading to all my live rock, snails, and hermit crabs. The structure of these things is tube like and they always seem to form a circular shape.

My question is what are they? and how can I get rid of them without hurting any other inverts?

Thanks,
Chris

 

[Fluff]

Serpulid worms. Small feather dusters. They are harmless filterfeeders. Manually removal like your doing (scraping) is best.