The dirt-caked tube was finely carved out of bone and had a perforated, threaded screw cap.
Crewmen aboard a World War II bomber etched their lovers' names on board. But that didn't save the plane from a grim fate.
Whatever the fortunes of digital currencies, they are a major shift from centuries of history that relied on tangible money instead of virtual.
Some critics sarcastically refer to the single bullet theory as the magic-bullet theory.
From Castro to mobsters to the KGB, many theories still compete to answer one of history's biggest questions.