Had 'em both, Jeff, and I believe you saw them both as well. I'm still suspicious that my brittle star may have had something to do with a bicolor blenny's disappearance, but the Warren Report is still somewhat vague.
They were a black brittle and a grey serpent star, and both lived very happy lives in my 90 awhile back. Both, to the best of my knowledge, are in Dan Hinch's sump, and they're probably large enough that if they wanted to, they could take over the world.
I'd heartily recommend them, although I'd stay away from a green brittle. They do a great job of cleaning up detritus.