Crabs are tasty

So a few days ago I bought 2 dozen dwarf blue leg hermit crabs to help clean up the algae I had from my cycle, and keep things clean ongoing. I also got some extra shells for them, since I heard they like to move around from time to time. So when I first started to see some empty shells here and there I wasn't worried, because I'd thrown a bunch in to begin with. But I've noticed a few less actually grazing, and this morning I see one that is for sure dead on the bottom with a leg or something a few inches away from the shell. So I'm wondering if my fish are eating these guys. I have two clarkii clowns and one fairy wrasse, which I'm feeding twice a day right now. Any thoughts are greatly appreciated.

As a side note, these are great cleaners. I'd say about 90% of my sand was covered in algae the afternoon I put them in, and by 7am the next morning they had a good 75% of that cleaned up.

 

Hermit crabs shed their skin. Its more then likely thats what you saw

 

Yup, probably a molt.