Despite all our advancements in military intelligence, it turns out a simple coded message can still prove indecipherable. That's what British officials have learned after coming across a secret document from World War II that was attached to a pigeon courier — the skeletal remains of which were recently found in England. The message contains 27 blocks of five letters that would appear totally randomized to most people. Experts at intelligence agency GCHQ don't doubt there's real correspondence hidden within the text, yet translation is all but impossible without the accompanying codebook that would have been held by the message's intended recipient. Just who that was also remains a mystery; the document, written by a "Sjt W Stot," lists only "X02" in the "to" column.

Pigeons were frequently dispatched with sensitive messages during World War II, with the British ultimately using them to carry thousands of notes during the war. Clearly those responsible for crafting these codes knew just what they were doing. Even with the technological resources available to intelligence workers today, we're essentially left clueless as to what this piece of paper was meant to say all those years ago.