ID Please

[Graanks]

Bristle worm or Fireworm?

 

[MERKEY]

Look pretty fat for bristle....;Pompus;Vamp

 

[WheatToast]

Possibly Pherecardia striata, the Lined fireworm:

Supposedly a scavenger according to this site (under Amphinomidae):
https://chucksaddiction.thefishestate.net/hitchworms.html

However, I have found that they may consume desirable macroalgae, and various online sources state they will consume beneficial microfauna, such as brittle stars.