Black Hitchhiker - ID Please

[turban]

Hope I have got better pictures this time.

The first picture shows the black hitchhiker expanded.

The second picture shows it retracted into the hole when disturbed with a stick.

Below are further characteristics that I have observed:
1) It does not move away from this spot.
2) Velvet texture
3) When disturbed, it retracts immediately, and within seconds it expands back
4) I have seen it emitting small translucent particles at a rate of 1 particle per second after a large water change
5) It grows quite rapidly, it is now about 1.5 times larger than 2 weeks ago

Thank you.

Turban

 

[Anonymous]

I'm guessing peanut worm. Try checking it out at night, with a flashlight covered in red plastic. It may be even further extended.

If I'm right, it's harmless.

 

[returnofsid]

Kinda hard to see but it's kind of shaped like a flat worm. If so, they're bad!!