Visitors to the Petrified Forest National Park in Arizona remove several tons of petrified wood each year, often returning the rocks by mail, sometimes years later, with a "conscience letter" that tells stories of misfortune blamed on the theft: car troubles, cats with cancer, deaths in the family. Some writers hope that returning the stolen rocks will bring good fortune back; others simply apologise. The book combines original photographs of these otherworldly "bad luck rocks" with dozens of facsimiles of the intimate, oddly entertaining letters from the park's archives. Featured in the storyline of the Netflix series Dead to Me.