help! worm ID

[moo33284]

So I'm finding these tiny black worms all over. Skinny with a circular head out something. All black. I'm seeing more a lot more lately on my substrate and burrowed underneath next to glass. Are they harmful? Maximum size I've seen was a quarter of an inch and so skinny.

 

[moo33284]

Better pic of two

 

[moo33284]

Any ideas?

 

[aadair22]

http://www.extreme-aquatics.com/707/saltwater/how-to-indentify-worms-in-your-reef-aquarium/

Check out this link... Scroll down and I think it's like the forth or fifth picture. Hope it helps!