Is this a peanut worm?

[Dkmoo]

First time seeing the in my tank, its soft and squiggly, no visible legs, kinda just extend/retract like a tentacle, when it fully expands i can kinda see a small white mouth with tentacles poking around this rock area looking for food. Easily spooked, looks like the other end is attached to something and it kinda just pokes around in that area. (Pardon the cyano, currently dosing vibrant for valonia)

 

[Dolphins18]

Does it have tentacles like this on its mouth?

If so itd be a medusa worm.
Some say they can be dangerous, but theres literally thousands of different species, i've had a few that have been killed/eaten and have not caused problems. I am sure there are some specific species that may be dangerous, these are only my experiences with them.

 

[Dkmoo]

It's really hard to tell but I don't think its for feather/tentacles on the mouth like that..

From what I was able to see, it reminds me of the long tentacles that nassarius snails have.