A small painted tile is causing a big commotion among art-world academics. That’s because some scholars believe that the recently discovered piece is the earliest known artwork by Leonardo da Vinci: a self-portrait in which the artist depicts himself as the Archangel Gabriel. The work has been dated to 1471, when Leonardo would have been just 18 years old. 

Professor Ernesto Solari, who has written extensively on Leonardo, made the bold claim at a press conference in Rome on Wednesday, presenting his findings with the handwriting expert Ivana Bonfantin. According to Frieze Magazine, Solaris and Bonfantin arrived at their conclusion through a combination of technical analysis and research.

The academics used thermoluminescence dating to confirm the date of the tile’s firing. They claim an infrared analysis further revealed encoded inscriptions that point to Leonardo’s hand: a telling sequence of numbers and the artist’s signature in mirror writing along the subject’s jawline. The scholars believe both were visible prior to the tile’s firing but were rendered illegible by the kiln.

The date 1471 appears on the tile next to the numbers 52 and 72. Solari argues that 52 refers to 1452, Leonardo’s birthdate, while 72 refers to the seventh and second letters of the alphabet—G and B—which he says alludes to the Archangel Gabriel. “More than a signature, it is typical of the famous puzzles that he loved all his life,” Solari insisted.

Solari believes that Leonardo created the piece in his paternal grandfather’s workshop, who is thought to have been a ceramicist. The scholar says the tile was given to him to analyze by a member of the Ravello family, who were given the artwork by the Duchess of Amalfi in 1499 and have owned it ever since.

Solari and Bonfantin‘s bold hypothesis, however, has not been embraced by all Leonardo experts. The discovery was roundly dismissed by leading scholar Martin Kemp of the University of Oxford, who compared the subject’s hair to pasta. “The handling of the hair is spectacularly unconvincing—it looks like vermicelli,” Kemp told the Guardian. “The chance of its being by Leonardo are less than zero. The silly season for Leonardo never closes.”