Need an ID

[dseiler]

I was looking around my tank last night after the lights went out with a flashlight and saw a .....worm I guess..... that I have never seen before and wonder if someone could id it. It is very thin, maybe as thick as the lead in a pencil, white on the bottom with black on the top that tapers down into stripes that thin away. When the light hit it, it backed into itself into the rock where it's hole is.
I hope that is enough info. It does not seem to be hurting anything as my tank is very happy, but I was curious what it was.
Thanks for the help.

 

[dseiler]

Thanks Sammy. It is pretty wierd watching it roll into itself. I am curious what they feed on though. Is it one of those creatures where if you have one you will have a thousand soon?
Just wantin to know what roams in my tank.