ID my puking critter (pic included)

[sequential]

This little critter made itself known in the past three days by puking long, thin, stringy things into the tank. The excrement is similar to what an anemone might excrete, but much, much smaller. When the water is disturbed, the stringy thing appears to be retracted. I can't get a closer picture than this, unfortunately, but it looks like a tube, wound in a circle around the base, with an opening toward the center that faces up. When I touched it with my baster, it appeared to be rigid. If it's a tube worm, it has an imperceptible crown, but then again, the whole critter is rather small. I didn't notice it until it began puking.

The critter in question is directly in the center of this image:

 

[Andrew]

Tagging along. Ive got one of those on my rock as well.

 

[Javeo]

vermatid snail, harmless in the tank

 

[Lpabsolute]

I've got plenty of them in my tank, they are harmless

 

[sequential]

Thanks for the possitive ID.