What is the method used by the "Robber Crab" (Coconut Crab) to open the hard outer and inner shells of the coconut?

Vanuatu coconut crabs have to first use their claws to pull away the tough outer husk. Then they look for a weak spot in the inner coconut shell (usually the eye of the coconut) and stab it with their longest walking leg. Finally, they use their powerful claws to rip open the nut to get to the sweet flesh inside. The reward is worth it - coconut crabs that live on a diet of coconuts grow twice as large as those that don't!