Mobile Bay Reef Keepers

My wife saw this creature in one of our rocks today. She tought it was a brittle star's leg, but saw it retract like it might be some kind of worm. Anyone know what this is?

Sorry some of theses pics aren't the best but I think you get the idea.





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Peanut worm. They normally are very nocturnal.





http://www.seaslugforum.net/showall.cfm?base=sipunculid

thanks