Folks, if you've recently upgraded or renewed your annual club membership but it's still not active, please reach out to the BOD or a moderator. The PayPal system has a slight bug which it doesn't allow it to activate the account on it's own.
I used to have one in a 10g tank I had. Think gave me the heebie jeebies. Only saw it when I turned the lights on in the room after the lights in the tank were off for hours.
It is an epitoke, not a full worm. Basically, when certain worms, like bristleworms, reproduce, part of the worm that is specialized for reproduction breaks free and swims off. They swim in crazy patterns and are attracted to light.