[Sk8r]

My specimen rocks came back from boarding at the lfs with a horde of little hitchers. Got a fleeting good look at one today as it got onto the glass [it had ridden a snail up, and the lights cut on].

gray and black striped. Very small central body relative to arm length, compared to other brittle stars. One arm a third more developed than any other arm. Lives in holes in rock, and sticks that arm out, I'll suppose, since you don't see all of them usually. Greatest single arm reach, little over an inch.

They're everywhere. I don't think they're a problem, probably good cleaners, but if I've got one in my 54g I've got a hundred or so.

Any observations on them? ID? Good guesses? It's-ok or start-worrying?