The Kimbell Art Museum will soon be the only U.S. museum to display a Michelangelo painting after acquiring his earliest known work, a rare treasure that was tucked away and doubted as authentic for more than a century.

“The Torment of Saint Anthony,” is a 15th-century oil and tempera painting on a wood panel that depicts scaly, horned, winged demons trying to pull the saint out of the sky. Experts believe he painted it when he was only 12 or 13 years old.

And only four such works — including this one — by the artist exist, and two of them are unfinished. Most of his paintings are frescos, the famous scenes on the ceiling and wall of Rome’s Sistine Chapel.

Experts in the Met’s paintings conservation department carefully cleaned it by removing decades of dirt, as well as paint layers that art restorers had applied through the ages to fill in chips or dull areas, Lee said.

When they examined the painting further using X-rays and infrared technology, they were able to see how the artist made certain brush strokes, scraped paint layers to achieve detail and even changed elements of the painting before the final version.

The generations of dirt and paint buildup had obscured the painting’s identity, and some doubted its authenticity because a similar painting existed, Lee said. But an art expert who extensively studied both paintings said the other was done in the 17th century.

Michelangelo’s piece has previously been known as “The Temptation of Saint Anthony” because he was inspired by a similar engraving of that name while learning to be an artist. But after the Kimbell acquired the oil painting, Lee decided to change its name because that engraving depicts a different scene, he said.

The painting will be displayed at the Kimbell starting this fall after a summer exhibit at the Metropolitan Museum of Art in New York. Lee said he may loan the painting to other museums later for traveling exhibits.