Unknown black stuff on LR. Problem?

[hrdneglcry]

I've got unknown black stuff on one rock. It was on the dry rock when I bought it. Is it bad? Here's a PIC.

 

[clevername]

This is known as dieoff. This is normal for live rock, no worries.

You will however have to "Cure" the rock before putting it in the tank with fish/corals.


Wish i could type the full procedure, but i have to run. research "curing live rock"