Swimming Bristleworm?

[PotatoPig]

So I saw a pale-ish worm in the tank this evening, about 2-3” long crawling over the rock after lights out, and then suddenly it swam from the rock to the glass, climbed up the glass, swam a bit more, then got sucked through a power head and it’s tail cut off.

Anyway, the videos below are after the power head got it so it’s a bit shorter than it started out the evening, apologies for the bad focus on the last one as my phone wouldn’t focus on the right part of the screen.

Worm. Pale. Lots is small legs. Two small antennas at the head (not really visible in the videos).

Video 1
Video 2
Video 3

 

[Gtinnel]

Anytime I see a small worm swimming like that I instantly think epitoke. Which is not really a type of worm but more of part of the reproductive cycle of polychaete worms.
Essentially it’s part of bristleworms reproducing where the back end detaches and swims around. That back part of the worm that swims around is the only form of the worm that can reproduce sexually.