Maybe your mantis is still getting comfortable. So far, the only time I've seen phil attacking something with a shell like one of those, is when a large blue leg I put in for cleanup once walked in front of his burrow. As for the raptorials being lost, I'm fairly certain that's mainly O. scyllarus. One way I make sure phil exercizes his raptorials is when I feed him from the eye-dropper, once he's no longer interested/hungry, he hits it once to signal that, and I go on to feed the other tanks. (lack of exercise leads to "rap-loss", not lack of live foods. The rapto-ah heck i'll call em 'claws'- take a lot of energy to maintain, and if they aren't used enough, they are shed to preserve energy. They are also shed due to atrophy, which makes them useless if they're needed- if a mantis loses them they will regenerate, but can take up to a year or more depending on how often it molts (age), metabolism (more active and more food), food amount, and health of the mantis.) But if you find a way to make him more active, I'd like to hear it, Phils only taken down about 2 to date.