Crazy fast worm

[LardLad]

Any ideas what made this? It is a tube constructed out of mucus and sand that goes up into the rock. There is a little pile at the bottom.
I saw the worm at night with a flashlight. He is long and very thin and super fast.
Is it a Fluke?
This is a coral-only tank. I hope he is coral-friendly

 

[mdb_talon]

Spionid worm. Generally harmless. If close they can agitate coral but dont attack it or anything.

 

[LardLad]

Spionid worm. Generally harmless. If close they can agitate coral but dont attack it or anything.

Thank you.