My hermit crab died ? ;(?

Myy hermit crab, active , was as heathy as can be . he would really exsersize and play with me (without pinching ) i feed him and gave him water everytime he was out . i got him i gorgia last summer alont with another crab, but he killed that krab. but about cople days ago he died . the day befor he died he was just fine. I miss him so much !! What happend ?? : /