A daguerreotype of Phineas Gage discovered by photography collectors - it is the only know photograph of him.

Two photography collectors discovered this daguerreotype thinking it was of a whaler they posted it online. Soon they received many instances of feed back saying that he was not holding a harpoon. Upon further research in conjunction with Harvard and the Smithsonian they discovered that it is in fact a photograph of Phineas Gage (the famous neurological case.) It is the only known photograph of him and it was due to the clarity of the daguerreotype that they were able to read the inscription to make the connection. Please read the article here.