First these atolls are not volcanic. Second its easier to hunt for coconut crab in the shaded areas like you were in later in the video. Third locals plant coconut trees to mark that they have claimed the land as theirs so be careful on what you cut up. Its the equivelent of burning someones house down and claiming their property. I couldnt tell from the video if that coconut was purposley placed there or not. But by the lack of cocopalms around it I would guess it was.