Ricordea infestation, any ideas?

[Reefer Rob]

I have Ricordea spreading all over my SPS tank. They're a bigger pest than Aiptasia, although prettier. They end up stinging the heck out of my acros, and when I try to scrape them off they can pull themselves into a crack (just like their little buddies) I've tried boiling water, but they always bounce back. I wouldn't mind keeping a few if I had a way to control them.