The Appalachian Mountains hide something so strange that even locals avoid the subject. Beneath the ancient forest floor, explorers keep discovering odd formations that defy natural explanation.

The Appalachian Mountains do not look like they are hiding anything. There are no towering peaks like the Himalayas, and none of the dramatic presence of the Rocky Mountains. They are simply a series of soft green ridges running from Canada to Alabama, the kind of landscape most people pass without a second glance. That unremarkable appearance, however, is part of what makes them unusual. Beneath…