What is this scary looking worm!?

[Duncan Krebs]

I saw this thing cruising around in my tank late last night and then finally bunkered down in some rock, looks creepy like a parasite but i have no idea, anyone know what this lovely thing might be?

 

[Lionfish Lair]

Which direction was it going? Down or up?

 

[Duncan Krebs]

Swimming in all directions, looked like it was out of cover and trying hard to find the bottom again to bunker down, also made it to the surface a few times.

 

[Lionfish Lair]

I meant in the picture. I'm trying to figure out which side is the head. That looks like eyes on the bottom, but their's other things it could be.