white sac looking things in my fuge?

[cmsurfr22]

i have these white sacs in my fuge. they're attached to the rocks, walls, and chaeto. what are they? are they bad? how do i get rid of them? they aren't in my display tank where i can see.....i did however pick up a rock and i found on on the underside of one. i'm not sure if something is eating them in my display and that's why i don't see them or what? here are some pics:

i circled some of them but pretty much all of those small white dots are them

 

[Whitebird1]

I have then too. Seem harmless, just more life, may show a healthy system.
Greg

 

[cmsurfr22]

are yours only in your fuge? or are they in your display as well?

 

[Whitebird1]

in my fuge, but i have a 10 gal holding just rock and they are scatterd in there

 

[RichT]

They are pineapple sponges. I get them on and off all the time. Harmless filter feeders. Do a search on RC to confirm.

HTH