Do I have a predator in my tank?

about 2 months ago my algae blenny disappeared. I got another one 2 weeks after that and it disappeared. now I have noticed my goby/pistol shrimp pair have not been seen for weeks. now I somtimes I do here clicking sounds at night however I believe my trocua snails make a clicking sound when they twist there shells. now another reason im not thinking manits is becuase my angel fish and my 2 clowns have been in there for 6 months and they are still here. also non of my inverts have disappeared. my thorny star,blue leg, red leg hermits, scarlet reef hermit, nass snails, troc snails, cerith snails feather duster, have not been bothered. as far as carpet....I have not found any boides near or around the tank.....whats going on? btw. I do check for ammonia spikes when a fish comes up missing and my ammonia remains at 0.

 

can you be more specific on the starfish? thorny isn't overly specific. Some thorny star fish are predators.

 

Its just a Red Thorny Starfish. I highly doubt this starfish is a predator.

 

Hermits make clicking sounds too, as they bang their shells against rocks and glass while moving about. And while it's possible for any motive invert (stars, crabs, shrimp, hermits, etc) to become opportunistic if they're not receiving enough food, given that sessile inverts are not being harmed, it's more likely that the 'missing' have perished from internal disease or some other unknown reason and were consumed by the clean-up crew. With that many snails and hermits, it wouldn't take very long. However, I'd still recommend keeping a close eye on everything for a while, including using a flashlight at night, to make sure nothing has gone rogue on you, and you don't have an unwanted hitchhiker lurking about. If either is the case, you'll eventually catch him in the act.

Cheers