Need help identifying worm. Good or Bad?

I've had my tank for about 6 months. I've started seeing small worm like creatures crawling around the sand bed and in and out the rock. The worms are a clear like color, have tentacles and remind me of a centipede. Excuse my poor camera skills. I can email more pics if need be. Can anyone identify them? Are they good or bad? If bad, how do I remove them? Thanks
 
Pic is a little small to see what you got. Here are some good sites for ID-ing HHs.

http://bb.wetwebmedia.com/viewtopic.php?f=25&t=2257
http://www.chucksaddiction.com/hitchhikers.html
http://www.melevsreef.com/id/
http://www.xtalworld.com/Aquarium/hitchfaq.htm
 
I'm pretty sure it is an amphipod. They are common and good to have since they help process detritus and are themselves a food for many creatures. Amphipods are crustaceans.
 
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