Attack of the boring feather dusters!

[0sprey]

I had a few of these come in on a coral frag I purchased a few months ago.. they weren't visible at the time of purchase, but at this point, they have not only grown, they've reproduced like mad. Has anyone had really harsh experiences with these little fellows, or am I just being paranoid? They've thoroughly colonized the glass in my sump and are definitely spreading thoughout the rockwork in the tank, even though most of it is covered with coralline. I haven't seen any on my LPS just yet, but I'm starting to think it's only a matter of time...
Any suggestions for dealing with my recent plague?