Leslie's ID is a bit more specific than Jeremy's (which is accurate). Here is what she wrote about my eurythoe complanata:
"Those are Eurythoe complanata which is a scavenger and detritivore. They won't harm corals, clams, or anything healthy.
The big conspicuous species in the family Amphinomidae are all called fireworms. These include members of the genera Eurythoe, Hermodice, Pherecardia, Chloeia and Notopygos. Smaller ones have the same fiery effect but being overlooked by most people they don't get the honor of a common name.
Carnivorous just means meat eating and Eurythoe does eat meat. More importantly it's not a predator which goes after living or at least healthy animals. If a coral or clam develops necrotic flesh because of a disease or an attack by a real predator scavengers like Eurythoe or hermits will be attracted to it and move in to slurp up the dying flesh. Once started they may continue eating - I'm not sure if they stop or not. it may depend on whether they're getting adequate food.
Eurythoe's valuable in tanks as a detritivore eating excess food and feces. You can remove them or start limiting food going into the tank in which case the population will decrease as the food decreases. Gloves are always a good idea anyway - there have been cases of reefers getting nasty infections just from bacteria getting into cuts on hands."
