What is this on my zoas?

[Saltine]

Is this some sort of cyno? Thoughts? Seems to be irritating them but not the gsp.

Thanks
Salt

 

[jminick2]

does it blow off easily? it looks like cyano but its hard to say for sure

 

[VWD]

I agree with jminick2, looks like cyano

 

[Saltine]

It's currently in a very high flow area and it doesn't budge. Took a turkey Baster point blank and didn't move.

 

[jminick2]

ive had some coralline that color but it doesn't strike me as coralline. My vote would be cyano.

 

[Saltine]

It's a really dark red seems to be encrusted.