Worm identification and behavior identification.

[tjtax]

Saw this in my tank tonight for the first time. What in the world? By the way, I know my tank is a little dirty but I'm a CPA by day so this time of year is a little rough for pristine maintenance.

 

[shakacuz]

not sure what the orange figure is, but the red strands do seem like medusa worms.

 

[ISpeakForTheSeas]

Saw this in my tank tonight for the first time. What in the world?

That is some kind of bristleworm, probably a Nereid species, spawning in your tank.

Most bristleworms break off into pelagic epitoke for spawning, but some Nereid and Spionid worms exhibit a wider range of spawning methods like this.

Super cool to see, and - as implied - this is a fairly rare method.