The structures you asked about are stylets. They're attached to the eversible proboscis & used to inject toxins & digestive enzymes into prey.
Great photos. Do you have Nomarski, something similar, or using stacking?
Polychaeta..... Poly = many, chaeta = bristle or hair so these are bristle worms, marine cousins of earthworms. Fireworms (amphinomids), spagetti worms (terebellids), hair worms (cirratulids), fan worms & feather dusters (sabellids & serpulids) are just a few of the families in class...
It's an amphipod. Many species build tubes and some in family Ischyroceridae build these caddis-fly-like tubes.
Scroll down to see the Cerapus tubularis pic
Betta, the info on that page about syllids isn't right. Most syllids seem to feed by piercing plant or animal cells then sucking out the contents. Many are commensals; their feeding doesn't damage their hosts. A few - like the big one Travis' friend found, actually eat corals and those should...
Someone asked me to comment on this thread. The red structures aren't cirratulids or any other type of polychaete worm. I don't recognize them but then I'm a worm specialist and you all need a coral expert. Sorry.
Hi Kingfisher --
Got your PM. congratulations on catching the worm. I really hope it was the only one and you don't have to worry about any more. From your photo it looks as if you either got the whole worm or enough of it that you shouldn't have to worry about any bits regenerating.