hard white build up?

[lickyricky]

So i have been getting little "bumps" of hard white build up on the back wall of my tank...any ideas on what this is? is it normal...Is there a way to get rid of it/should I get rid of it? pic attached

 

[Troylee]

Tube worms aka feather dusters... Harmless.. You can scrape them off if you want there a eye soar that's about it..;)

 

[Steven R]

+1 tube worms have about a million of them in the sumps also agree that they are ugly little guys lol I suppose they serve a purpose though.