I have a few of these in the tank, this particular one is about 5-6" long. I'm guessing it's not a fireworm it doesn't look like most of the pictures I've seen of them.
Hopefully they won't go crazy in there I have 2 false percs in there already which is pushing it for a 12 gal. So no fish solution. Arrow crab and Coral Banded shrimp I'm not too thrilled about either. I guess if I start seeing more and more I'll try the baited pantyhose and/or Coralife trap.