my boxer shrimp!

Pls help!!!

my boxer shrimp just died. but the way he died is puzzeling me. he died
seperated from his shell. his shell was in one whole piece including all the
legs, tail, feelers etc. and his naked body is just nearby.

if i am not wrong, shrimps, lobsters they de-shell themselves when they are
growing too big for their original shell so they can grow a new shell. but
in my case, why did he died in such a way? could it be he's also going thru
the growing process but ended up dying. i have a small size scooter blemy
and a really small box fish and they have been living peacefully together
for weeks. so i dun think they are the cause of the boxer shrimp's death.

pls help............