Things are disappearing in my saltwater tank please help me?

I hve a 29 gallon tank with a 1.5 in. pistol shrimp, 2inch Ocellaris Clownfish, 1.5 in. Yellow Watchman Goby (never bonded to the shrimp they avoid each other, some tiny aiptasia, a 3 inch long worm (fire or bristle that is pink and white), some big netrite and sand sifting snails, 2 tiny hermits, and maybe a purple lobster. I say maybe because I haven't seen him in a month or 2 and I used to have an ell that bit his claw off once. I think it might have been crushed when I moved the rocks all around getting the eel out. Ok so on sunday, I added 3 liverock pieces to my tank. One is a small stone, one is about a foot long with aiptasia and bristleworms on it with a bunch of tiny holes in it, and one is the size of a big grapefruit with alot of hollow spots in it. I bought them from the stores display tanks as far as I know, no mantis shrimp was in the tank. On the second day of adding them, both my cleaner shrimp and pistol shrimp molted. The cleaner shrimp disappeared I found bits of him throughout the tank. I know he is gone now there is nowwhere he could be hiding and It has been days. I was mad after paying 25 bucks for it. Three days later, my sea star and hermit crab have gone missing. What is going on??? Could it be a mantis shrimp? I hear clicking but it is from my pistol shrimp I think and I saw him a day ago so he is okay. Any thoughts on what is happening???