So sorry you have that stuff.
I had it in my last 180 SPS reef. I can't remeber the name but it likes high light and low nutrient environments. Margarita snails ate it, not much else. I went with elevated ph using kalk, ozone, and a monster skimmer. eventually it faded. Don't know if it was something I did or it was just the passage of time. I makes green hair algea look like a blessing. If you give it more light, it looks exactly like cotton candy.
Don't trade frags with anybody until it is really gone. That is how I got it in my tank
Bill