What are my crabs doing?

[Dearth]

My sand bed is littered with shells but my hermits ignore them and will always either chase another crab out of its shell or kill a snail for its shell I've lost 5 snails so far this way. If you plan on keeping hermits plan on them taking shells from the living I have yet to see a vacant shell being used as a residence. I will do another snail order this spring to replace my depleted snail population.

I just end up plucking a few shells out for my nieces every few weeks just to clean up the clutter.