I originally thought it was some type of grape caulerpa but I can't find anything that looks like it. So I decided to let someone else with more experience look at it.
Yea, I woudlnt mind that so much in my fowlr tank. I think emeralds will take out bubble algae, it might take this out too. Im sure with more salt experience could confirm/deny this.
EDIT: My track record with looking up algae is not so hot. From the pic provided though, it looks attractive and it looks like a macro of some sort. I, of course, am no biologist nor botanist.
I do like the look of it i just wanted to make sure its not a harmful type and yes it did just grow up out of nowhere. I am in a never ending battle with hair algae with this tank. Here are a couple more pics with a better camera.
My clown being photogenic.