Before candy hearts, there were Valentine etchings.
Case in point: a romantic message carved into a piece of bone more than 900 years ago in Sweden.
"Kiss me," it says.
The markings had stumped scholars for ages.
But a scientist at the University of Oslo recently cracked what's known as the jotunvillur code, a secret rune language used by Vikings in the 13th century that can be found in more than 80 Norse inscriptions like the Viking Valentine.
Runes are letters in ancient runic alphabets, which were used to write Germanic languages before the adoption of the Latin alphabet.
More from GlobalPost: True love means you give me your password, according to the Pew Research Center
"It's like solving a puzzle," scholar K. Jonas Nordby told the Norwegian website forskning.no. "Gradually, I began to see a pattern in what was apparently meaningless combinations of runes."
Anyone hoping for some deep, dark Norse secrets will find themselves disappointed.
Most of what's been decrypted so far appears to have been used in learning or written in a playful tone.
In many instances, people who wrote the codes left comments urging readers to try to figure them out. Some even boasted of their coding abilities.
Nordby's findings were recently published in the International Journal of Runic Studies.