Right. These guys are by and large absolutely harmless and beneficial. The vast majority of those encountered in aquariums are beneficial. Very rarely will you find one that causes problems--these include fireworms (distinct from what most people call 'fireworms'); some eunicids (stuff of legends--big); and Oenone fulgida, which dines on large, swimming fish.
ok im cool with them i just looked in my tank with a red light for the first time and was like whoa!!!!! what is going on and then i look at my star polyp and saw one in it and was like they got to go i just got my devils hand & candy cane thanx chris so i was like noway they are getting them