Thanks folks! Going to give it a shot. I have two plateaus that will work great and should look really good covered in something. I was hoping the Coraline algae would do it, a I guess it would given time. I have some purple and light green spreading already. I actually thought one of my shells had green slime on it until I tried to scrape it off. Its pretty hard and upon a closer look, appears to be the Coraline.
Is there a special name for the Zoas? The ones I'm looking at have a red to rust coloured center with a green "circle" around them. About 15 centers (heads?) per frag.