In 1592, a British ship sank near the island of Alderney in the English Channel carrying an odd piece of cargo: a small, angular crystal. Though cloudy and scuffed up from 4 centuries at the bottom of the sea, its precise geometry and proximity to the ship's navigation equipment caught the eye of a diver exploring the wreckage. Once it was brought back to land, a few European scientists began to suspect the mysterious object might be a calcite crystal, which they believe Vikings and other European seafarers used to navigate before the introduction of the magnetic compass....