You probably haven't heard of L'Inconnue de la Seine (the Unknown Woman of the Seine) but there's a good chance you've kissed her directly on the mouth, in a manner of speaking.

In the late 1880s, the body of a young woman was discovered drowned in the River Seine in Paris. Nobody knows what happened to her, though at the time it was speculated to be suicide. More importantly, nobody at the time knew who she was either.

Unlike today, when a face might make the papers or be posted on the Internet, in 1881 France, as a way of hopefully getting an identification, officials would often take a corpse and place it in the window of a chilled room for people to gawp at like an item in the window of Trader Joe's.

Should anyone recognize your corpse they could then say something along the lines of "I'll take that one to go," like you would if Trader Joe's had table service.

The viewing windows were weirdly popular with people at the time. “There is not a single window in Paris that attracts more onlookers than this," according to a volume of engravings from Unknown Paris (1893), which suggests it wasn't just people with missing friends and family that would take a peek, but passing members of the public. Don't judge them too harshly, entertainment was thin on the ground back them, for instance, not one of them had yet watched Disney's Ratatouille. 

However, nobody claimed the unknown girl, thought to be about 16 years old. She was placed in a pauper's grave, but not before one last slightly creepy person took something from her that would endure for centuries after death: her face.

It's not known why the pathologist at the mortuary decided to make a death mask of her, though the popular story goes that he was so entranced by her beauty that he couldn't help himself, which is a good indicator that he probably shouldn't have been working in a mortuary.

For whatever reason, the cast was made. It became bizarrely popular when it was taken out of the mortuary and masks made from it went on general sale. People apparently could not get enough of this dead girl's face. It was popular among artists and writers alike; stories were written based around L'Inconnue de la Seine, inventing backstories for her and how she was murdered, or how she came to drown herself in the river. The mask became something that everybody needed to have, like a Furby in the 1990s, except it was a corpse's face.

There was even a horror story based around the death mask where it goes on to kill a bunch of people, which is essentially the opposite of what fate eventually had in store for it.

Her face endured for decades, when in the 1950s a toy manufacturer, Asmind S. Laerdal, used the model as the face of a soft plastic doll named Anne.

As chance would have it, Laerdal's own son had nearly drowned when he was 2 years old. When, in the mid-50s, Dr Peter Safar came up with a method of resuscitation involving mouth-to-mouth and chest compressions (CPR), he went to Laerdal for help with how to teach it around the world. Laerdal leaped at the chance, and together they worked on a lifelike(ish) CPR doll that if you've ever done any kind of first aid training, you've probably pressed your lips against, the Resusci Anne.