A rough box crab (Calappa gallus), which I have also seen in Indonesia.

(Blue Heron Bridge, Riviera Beach, FL)

arthropod; crustacean; decapod; crab; box crab; rough box crab; Arthropoda; subP Crustacea; Malacostraca; subC Eumalacostraca; supO Eucarida; Decapoda; subO Pleocyemata; infraO Brachyura; supF Calappoidea; Calappidae; Calappa gallus