Possible hermit killers

[shadow puppet]

Well, recently I've found a couple hermit crab shells in my tank, that have holes in them, and was wondering if anyone might know what could have done this? The shells looked like they were already well bleached, pale white etc... Also I had some wavy looking worms on my live rock, and they are gone now, as well. I know, not very descriptive, but the best i can describe them as wavy worms, they looked like grass or something, but I was told they were actually worms.. All I have in the tank is a velvet damsel, and a Potters Angel, along with 16 lbs LR.. maybe a mantis shrimp? but wouldn't it have eaten them before now? as I added hermits long before I did any kind of fish.

 

[fshhub]

it cold be, a mantis, go hunting at night with a flashilight and use a red lese, see if you cna spot one, and if ti were small, then it may not have needed the hermits for foood, could have been eating the worms
HTH