A shipwreck in the English Channel may have yielded quite a treasure: Scientists think they've found a Viking sunstone, the mythical navigational aid Viking mariners used to locate the sun and traverse the sea before compasses were developed. A crystal found in the wreck of a British ship that sunk off the island of Alderney in 1592 could have been used as a sunstone, they say, according to the BBC. Sunstones were once considered "mystical," since they were said to be able to pinpoint the sun's position even through the clouds, but a 2011 study found the stones were actually real.
The crystal, an oblong shape about the size of a pack of cigarettes, was found near the navigational equipment. And it's an Icelandic spar, the type of crystal scientists say the Vikings used, because it can diffract light into two distinct rays. Scientists tested a similar crystal and found it was indeed possible to determine the direction of the sun by finding the point where the rays converge, even after the sun has set. Though the British ship on which the crystal was found sailed long after the Viking era, scientists think sunstones continued to be used for centuries as a backup to the compass. As for why no intact sunstone has been found at a Viking burial site, scientists think that could be because the crystals shattered when warriors were cremated, the Independent reports. (Read more Vikings stories.)