Help With ID? Looks Like Cyano, but...

[Dinkins Aquatic Gardens Verified Sponsor]

Can anybody help me out with an ID? It looks like green cyano to me, and in some areas forms mats while in other areas it just remains "speckled" across the sand. Some of it is easy to blow off, but I have this stub

born dark green/black spot on a prized coral plug that won't blow off. I'm on hour 36 of chemiclean treatment with absolutely no results so far.

 

[EeyoreIsMySpiritAnimal]

Can't really tell anything with the over-blue pics.
Also, need your parameters, size and age of tank, lighting, flow, etc.