Worm on snail shell

[BloopFish]

Found this worm crawling out of an empty dwarf cerith snail. I'm pretty sure I don't remember it being empty and lying there before. Any clue on what type of worm it is?

 

[stanleo]

I saw an amphipod crawling out of it. Not a worm and a good thing to have in your tank.

 

[stanleo]

NVM. Now I see the worm, didn't watch long enough. Looks like a dorvilleidae worm. Also good to have.

 

[reef lover]

Idk ....the head looks odd for a dorvellidae i would remove to be safe.