I have this black algae, any one know what it is?

[fishski13]

Been looking around online but couldn't find much info on this. Its a black algae and its hard and cannot come off the rock. I was thinking it might be coralline since I have purple and red growing throughout the tank but I am not sure. Does anyone have any idea or experience with this?

 

[Timfish]

Looks like some kind of cyano to me. It should siphon off pretty easlily. If it's a sponge it will take a little more work but it should siphon off also.

 

[vetteguy53081]

Appears to be cyano. verify by taking a turkey baster and gently blowing water bursts on them. If they dislodge, net the loose stuff up and verifies cyano. If not , may be sponge or algae

 

[fishski13]

Appears to be cyano. verify by taking a turkey baster and gently blowing water bursts on them. If they dislodge, net the loose stuff up and verifies cyano. If not , may be sponge or algae

I already tried that, thats why i said its hard and doesnt come off the rock. That what lead me to coralline but have never seen black.