Crazy-Eyed Crab

When we go fishing in South Kona, we see a lot of these shed crab shells on the rocks. This one was so perfectly intact that it looked alive and kind of scary with its white bulging eyes. I wonder why they molt on the rocks because they're not protected from predators as their new shells are soft for 3 or 4 days. Maybe there are no predators to fear, other than humans.