Help ID: nudi with long stringy tentacle

[-JoJoReefing-]

Get this nudi-like hitchhiker from TBS live rock. Seems to appear more often after lights out. Mostly transparent, a little green/brown. Have two very very long stringy tentacle extending from its front and end, the stringy tentacle is very thin and has a comb-like structure.

Good or bad? Anyone can identify it?

 

[-JoJoReefing-]

 

[Kasrift]

Those look like flatworms and not nudibranch…

 

[-JoJoReefing-]

Those look like flatworms and not nudibranch…

They seem to flat out when dead; looking from the side or top they look very much like some nudi with those little tips and structures. Wonder if any flatworm would have tentacles stretching out? So far I only know a few common flatworms, all are very “flat”

 

[Kasrift]

They seem to flat out when dead; looking from the side or top they look very much like some nudi with those little tips and structures. Wonder if any flatworm would have tentacles stretching out? So far I only know a few common flatworms, all are very “flat”

Got it, I couldn’t see structures like that from your photos.

 

[ISpeakForTheSeas]

I’m super late to the party here, but long, stringy, comb-like tentacles sounds like it may be benthic ctenophores.

It’s generally recommended to remove them if that’s what they are