Way back in the day, my LFS had a colony of tiny pale filamentatious worms living in the substrate of a reef tank. I transplanted a good size culture of them into my FOWLR, and they propagated and heavily populated the substrate bed. I then introduced a Mandarin to the tank and it thrived on those worms. They were really tiny, maybe less than 1/16" long, and hardly any thicker than a hair. I would so love to find some of those worms today; is anyone here familiar with them ?