I have definite yellow coraline algea in my tank. One rock, when I first got it out of a 5 year old 75x6 gallon holding/display tank with about 2 lb/gallon LR, was about 20% covered with it. It died off nearly completely in my tank at first. However, within the last few months, it has started making a comeback. It is about the color of a bananna. The rock is at the highest level of my reef. I don't know if that is what made it die or that is where it likes to live. However, I do have about 3 or 4 small (2-3 cm) patches that have taken hold on the original rock.
I do have some really pretty small orange/pink sponges growing profusely on the bottom of a shady ledge rock of mine, but they are obviously sponges. Also some plain black chicken liver sponges.
I hope it keeps growing back the way it was...Collin