Can someone help me identify this hitchhiker.

[whitasm]

Just saw this floating around in the bottom of my bare bottom tank. Took it out for some inspection. Included pictures of what I would along with the rock if that would help identification. Thanks!

 

[ISpeakForTheSeas]

Looks like it may be a peanut worm (Sipuncula) - if so, it's harmless/beneficial.

 

[whitasm]

Looks like it may be a peanut worm (Sipuncula) - if so, it's harmless/beneficial.

Great, it was kinda weird looking and the head of it would come out kinda looking triangular but for the most part wouldn’t move much. Maybe it was dying and fell out of the rocks.