Worm ID

[Cable]

Any idea what this is don't think it's a standard bristle worm.

Thick head that looks like a bristle worm that slowly gets thinner and has no bristles.

Fell out of a rock during a dip (coral is in qt)

I can microscope it if needed

 

[reefer37160]

I have had a few bristle worms fall out looking like that during a dip, and some times they are completely retracted being very short and fat.