Red wormy thing...

[noone]

As I was adding water to my tank last night, I did minor re-aquascaping. I noticed a little red worm-like thing on my rock. As I proceeded to remove it, I kind of cut off part of him. Did I remove (and, I guess, kill) something that should have been left in my tank?

 

[Fluff]

Did it have bristles? Most worms are harmless scavangers but it's hard to say without a pic or more detail of the critter.