Standing on the sand beside a blue lagoon, Steve Schultz of Purdue University delivered the kind of verdict that expeditions dread. "Unfortunately, we weren't able to find that smoking gun," he said. The object that had drawn a 17-person team to the atoll of Nikumaroro, about halfway between Australia and Hawaii, was not the wreckage of Amelia Earhart's aircraft. It was a clump of washed-up trees.

The search began with satellite images from 2020, which showed an elongated white shape lying in the shallows near the Taraia Peninsula. Veteran Earhart researchers quickly suspected a fallen tree. Richard Pettigrew, who heads the nonprofit Archaeological Legacy Institute, disagreed after reviewing other images, including aerial video that seemed to show a metallic glint in the water. His doubt was enough to justify a multi-day voyage by ship, followed by weather delays, and four days of fieldwork that included metal detecting.

Because of the huge coconut crabs, nicknamed "robber crabs" for their habit of investigating anything that might be food, the crew slept offshore. Purdue's explanation is a neat lesson in how nature can imitate evidence. The reflective surface, it said, came from a carbonate veneer, and other objects found by the team were coated in the same shiny, hardened mixture of coral sand. The "metal" was geology at work.