Tube Worms?

[SWBeginer]

So many of these are in my sump and some of them already got in the show tank.

Are those white 'stuffs' are tube worms? are they good or bad? how to control them?

 

[gonzalez78]

i used to scrape them off the side of my tank with a single edge razor but mine never got that bad.... i do believe they are tube worms