This year marks the 800th anniversary of the Magna Carta, and the British Library has marked the occasion by assembling the largest ever collection of Magna Carta artifacts and related memorabilia. Included in that display is a 13th century medieval sword with an unsolved inscription.

The double-edged sword, which is on loan from the British Museum, was found in 1825 in Witham, Lincolnshire—more than 100 miles away from the field in Runnymede where the treaty was signed. It's likely of German make, and it is displayed next to a 14th century manuscript with illustrations of the 1203 invasion of Normandy which features knights and noblemen wielding similar swords. Along the blade is a gold-inlaid inscription reading:

+NDXOXCHWDRGHDXORVI+

Julian Harrison, the British Library's curator of pre-1600 historical manuscripts, posted on their Medieval Manuscripts blog that the inscription has yet to be deciphered, though he says "it has been speculated that this is a religious invocation, since the language is unknown." And thus, he's asking the public for assistance. Many commenters have put forward theories that the letters could be an acrostic for a saints' poem, or words or abbreviations in Latin, Welsh, Irish, or Sicilian. Any enterprising, ancient language experts (or amateur sleuthing enthusiasts) should join the conversation!