ID on this macro algae?

[asylumdown]

Took this clump that was growing across the sand of one corner of my display out today:



The picture doesn't really do it justice, under the blue LED lights the white swirls on the leaves were practically glowing. It's really quite a pretty plant, but I don't want it taking over my tank. Assuming it's not something really nasty, I'm happy to give this clump to someone with a macroalgae dominated refugium...