strange creature in my tank

Question
I have seen what looks like a long centipede in my tank moving through the holes in the rocks. Is this a normal thing or should I investigate further? I have a small 12 gal tank with 11 lbs live rock, several pieces of coral and three fish, a clown,pearly jawfish and 1 other I can't remember his name. I do water checks once a week. thanks for your help

Answer
Look up info on a fire worm, bristle worm also. See if the pictures match a fire worm, if it does you may want to take him out he can sting your corals. You can get a trap from your LFS or online. A bristle worm not as bad, if there is enough waste in the tank it shouldn't bother your corals, just keep an eye on this if it poses a threat take it out also.