Long, transparent tentacle with wriggling head coming from live rock

[Mike N]

After feeding my tank last night, I noticed some motion and took a closer look. It was a long transparent tentacle coming from the live rock. The head was wriggling around pretty good. I took video with my phone, I apologize for poor quality.
Make sure to view in 1080p:

I've gotten pretty good at identifying hitchhikers thanks to this forum, but this one is stumping me. Any ideas?

 

[DSC reef]

I'm stumped, possible ribbon worm?

 

[Mike N]

I'm stumped, possible ribbon worm?

I don't think so because I see no branching the in tentacle.
Just a single long tentacle, the head area has a slight white hue. There is no visible tube or foot.

 

[DSC reef]

Definitely odd. I don't like worms in the reef tank. Lol

 

[KJ]

I think it is a Peanut Worm.

 

[KJ]

 

[Mike N]

I think it is a Peanut Worm.

Yeah, I think you are correct. Thanks for the ID/video.

 

[KJ]

YW Mike.