What is it and how do I get rid of it?

[68sting]

I have two coral with a black looking substance on them. What is it and how do I get rid of this?

thanks

 

[68sting]

better pictures

 

[phillipj2]

I am no expert but it could be some kind of bad algea growth taking them over. Its hard to say.

 

[LooseHip]

the first pic kind of looks like cyano...