Stuff on my LR?????

[erhodejr]

I have some white slime looking thing on one of my liverocks, It kinda looks like a spiderweb. I have no idea what it is
Is it good or bad for that?
What do I do if it is bad??

 

[van888]

I have this also it's a type of sponge. Has never done any harm in my opinion.

 

[frozenice]

I had that on my rock when i first bought it. i just tore them off and threw them away, never came back.