Pastel blue and pink worm?

[supergiantrobot]

I did a water change in my aquarium today -- enough to expose about the topmost fifth of the highest-placed Marshall Island live rock in the aquarium. Much to my surprise, this evening, under the blue LEDs of the moon lights, I spied a pastel pink-blue worm sticking out of the rock.

I have never seen it before. It looks like an earthworm, round, about a half-inch or so in diameter, but irregular in diameter somewhat grainy in texture, and colored (at least in the blue moonlight) a soft pastel blue or pink. It does not like the flashlight.

What is it?

 

[supergiantrobot]

Here is another image.

 

[Anonymous]

I would guess it is a peanut worm. If it is it is harmless. Good find.

Does it retract back into it self like when you pull the tip of a sock back through itself?
Andy

 

[supergiantrobot]

I will have to watch it to see if and how it moves -- I see that peanut worms are so-called because their usual state is introverted in the shape of a peanut.

 

[Anonymous]

I would guess it is a peanut worm. If it is it is harmless. Good find.

Does it retract back into it self like when you pull the tip of a sock back through itself?
Andy

I agree with Andy here. Looks like a Sipunculan.