Fuzzy white hairs

[JKay]

Hello Everyone, I was wondering if anyone knows what the fuzzy white hairs that's growing on my live rocks and looks like it's spreading. Pictures doesn't do any justice but it's the best that I can do. Should I be worried about this? Thanks in advance

 

[Ocelaris]

I get that under rocks sometimes, I assumed it was bacteria or something benign. It's never hurt anything so I leave it alone. My tank is a year and a half and I still have those sometimes.

 

[JKay]

The crazy thing is it's starting to spread like crazy. I'm just worried it's gonna spread through out all of my rocks.