Mantis shrimp in there (or not?)

[fkshiu]

Here's the evidence:

The current tank (a 6' long 120 gallon) is now about 1 month old. All parameters have been consistent and are in good shape.

About half of the live rock came from my old 46 while the rest was cherry-picked from a number of reefers. In short, there's a wide variety in there. I "cooked" the new LR in the dark for about 6 weeks in hopes eliminating any ich and nuisance algae that may have tagged along.

I introduced an expanded clean-up crew about a week ago consisting of astreas/ceriths/nassarius snails and some scarlet hermits.

Yesterday I introduced a couple of blood shrimp, 2 porcelain crabs and a fighting conch. This morning everyone was doing well. One of the bloods had started exploring further down towards the middle of the tank while the other one stayed put in the same corner that I had originally introduced them.

I came back home this afternoon and found half of a blood shrimp carcass in the middle portion of the tank. It looked like it had been chopped in half. I could not locate its tail portion. The other blood was still in its corner.

About 6" away I find a hermit's body which looked like it had been ripped out of it's shell. It doesn't look like a molt.

Strangely, none of the nassarius snails were doing their usual "vulture duty" on the shrimp's body despite some juicy chunks of shrimp meat dangling out.

However, I have NOT heard any clicking noises, but it's a basement tank so I'm not always close to it.

Aside from the old clean-up crew, corals and a tuxedo urchin, the other residents are a regal blue tang, a royal gramma and two oc. clowns. They seem fine.

I set up a mantis trap by chopping the top off of a water bottle and inverting it back into the body of the bottle. I put some mysis inside for bait, but so far I've only managed to trap some nassarius snails.

Any thoughts???