ID Please?

[cajundolphin7]

Can anyone tell me what this is on my liverock? They are small and kinda offwhite but It does not move and doesn't have any tentacle like extentions like feather dusters. Is this harmful to my tank?

 

[luca brasi]

Hard or soft?
Hard= my guess is dead vermitid worms
soft= my guess is sponges

 

[subee950]

looks like sponge to me every now and again i get a little of this on my coral rocks from the lfs i never had a problem with it.

 

[mr.clownfish]

+1 sponges

 

[texasmetal]

Look more like vermetid snail tubes to me.