For more than three decades, biologists have carried out quarterly surveys of Bobcat Cave in northern Alabama, a site that sits beneath the secured grounds of the US Army's Redstone Arsenal and is already home to a well-known endangered species, the Alabama cave shrimp. After 30 years of closely monitored fieldwork in one of the most thoroughly documented cave ecosystems in North America, researchers have now identified an entirely new genus of eyeless cavefish quietly living in the same pools the whole time, hiding not through concealment but through an almost perfect physical resemblance to a completely unrelated species that shares its habitat.