Is this a brittle star???

[kae_shields]

I am fairly new to the saltwater/reef aquarium hobby. I have admired it for years, and now I have my own 65 Gal tank with about 60 lbs of liverock. I have recently noticed anywhere from 2 to 4 or 5 long thin extensions protruding from a small hole in one of my pieces of liverock. They appear to be about 1 to 2 inches in length, and only appear at night when my tank lights are off. If I shine a light on them, the retract back into the rock. Could this be a brittle star living inside the live rock? I never see it come out of the hole, (in fact, the long arms pretty much take up the entire diameter of the hole when they are extended) and I thought brittle stars lived in the sand or under liverock and came out at night. Thanks for any help in indentifying this mystery. -Kevin