Dark Stuff groing on live rock??? Help

[thetabors]

I have this black stuff growing on my live rock. I just completed my cycle and have alot of what my LFS calls brown algea. But this is new and it started yesterday and has already spread to another rock. I wiped some off and under it is white. Is this stuff bad or good??? What do I do with it?
Im trying to get a pic up but I am having trouble any advice on that would help too?

 

[wfd1008]

looks like cyano (AKA-slime)

 

[grim_reefer]

i agree with wfd1008.. cyano comes in a variety of colors

 

[earlybird]

Do a search on here for cyano or cyanobacteria. Lots of good information on how to battle it.