Locals living on the island of Vangunu in the Solomon Islands sing songs about vika, a giant, tree-dwelling rat that can crack open coconuts with its teeth. But scientists had never seen it.

Tyrone Lavery, a conservation ecologist at The University of Queensland and The Field Museum of Natural History in Chicago, searched for this rat for years. But the closest he got was a mysterious dropping found on the forest floor that contained the hair of some unidentified species of rodent.