I have this algae too and boy it is about ruining my hobby.
I got this in a 30G cube. it is the ONLY algae in tank. Here is a list of critters currently/in past for algae control:
1: Tuxedo urchin (currently): Does not touch the stuff... picks it up to put on his back though, spreading it further...grrr
2: Nicaraguan Pygmy sea hare (past): Does not touch the stuff
3: Emerald crabs (current): doesnt touch the stuff
4: Asst Hermits (current): Nope
5: Nasarius, cerith, Mexican turbo, trochus, astrea (ninja and reg), margherita, chestnut turbo snails (all current): Nope nope and nope
6: Baby Naso tang (past): Ate every single cell of it from the tank. 2 weeks after he was removed due to job well done, came back full force.
I got sick and tired of it after the naso incident, and removed all rock that had it, and all tank items were removed and bleached if infected (pumps, valves, tubes, grates etc.) And it was GONE for about a month
So i have stripped bare rock and tank with no coraline to speak of due to emeralds and urchin, and yet this stuff is STILL COMING BACK in patches!
AAAAAAAAAAAAAAAAHHHHHHHHHHHHHHHHHHHHHH!!!!!!!!!!!!!!!!!!!!!!
I am at wits end. Seriously if you see this stuff, take the rock/coral that it is on and throw it out the window A.S.A.P. im dead serious this is the worst macro algae i have ever seen, and i WORK at a lfs!!!
My next action i think is to bring all of my rock and infected corals into work and stick them in the algae eater tank crawling with hundreds of emeralds for 2 days and then we will see.
I told my GF that if it showed up again i would sell the tank, and she wont let me