Yar
 

Its amazing at night if your trigger was stung and killed, the bristle worms would gorge on your trigger. I have had fish simply vanish. You may have a mantis shrimp as well. Spear type or puncher...

I stronglt recomment yellow wrasses.Had 3 then 2 paired up and the 1 left died. They do a great job on bristle worms.

you have two large (long tip? or condylactus? anenomes)
they most likly ate him in the night... when fish fall asleep they tend to drift into the anenome
and get overwhelemed and trapped, after a few hours they spit out the remaining undigested food, which is generally finished off by the other inhabitants (worms etc)
and never seen again:(

its happend many times in my tanks over the years

Both Nems are BTA's he was really too big for them to eat without some leftovers.
The tank is not that old so there are not that many worms right now.
No mantis or other crabs as all rock has been with me for some time, and i only have about 10 small blue legs so I don't really think they would have finished him off that fast. I still think he jumped that or my cat likes fishing.