Gustave Courbet’s infamous “The Origin of the World,” an intimate portrait of a female model’s nether regions, has been shocking pretty much since it was painted in 1866. Even more shocking, though, is the fact that the painting has an upper half, which has been discovered by an amateur collector among yard-sale detritus.

The canvas, which was bought by the anonymous collector for $1884 from a Parisian antique shop in 2010, pictures the tossed-back head of a woman as seen from a low angle. The model’s jaw and strong cheekbones dominate the portrait, while a mountain of dark hair surrounds her face and cascades into the background. The portrait is painted in Courbet’s signature realist style — the model’s skin is flushed and uneven and her musculature is clearly delineated. She’s individual and unidealized, yet erotically charged.

According to the French Liberation, the collector noticed that the edges of portrait canvas were cut and that the work was not signed. Then, the art-buyer had an epiphany: They matched up the edges of the portrait with the contours of “The Origin of the World.” After researching Courbet’s work further, they found that the model in the portrait was Joanna Hiffernan, an Irish model and mistress of the artist who appears in many of his other paintings. Hiffernan was also the subject of “The Origin of the World.”

The Telegraph reports that the collector was able to align the two fragment paintings based on the grooves of the original wooden frame and the grain of the canvas as well as the brush strokes, which matched. Despite the evidence provided by the buyer, experts are not wholly convinced about the authenticity of the work, however. Researchers at the Center for Analysis and Research in Art and Archaeology supports the claim, and the piece has been entered into Courbet’s catalog raissone. The chief curator at the Courbet Museum “is not convinced,” Liberation reports.

“Origin of the World” was originally commissioned by Khalil Bey, an Ottoman diplomat and ambassador. He collected erotic pictures, including works by Ingres and other Courbet canvases. Courbet is thought to have cut the head off from the explicit portrait in order to avoid scandal for Hiffernan — such an unclassical, realist depiction of a nude body was highly unorthodox for the time. The painting still causes a stir. As recently as 1994, a book published with “Origin” on the cover was removed from bookstore windows.

A sketch published of Courbet’s work around the same time shows a full-body portrait of Hiffernan, leading to the possibility that a full “Origin” exists somewhere out there, just waiting to be reassembled. Given the impact that the first canvas had, one wonders what the completed piece could do. The newly revealed portrait is estimated to be worth as much as $55 million.