CONCORD, Mass. (AP) — A drawing purchased at an estate sale in Massachusetts for $30 is believed to be a rare work by a Renaissance artist worth tens of millions of dollars.

International art experts say the previously unknown drawing by Albrecht Dürer could be one of the most significant art discoveries in recent memory, The Boston Globe reports.

The pen-and-ink drawing is about the size of a children’s book and depicts a seated Mary holding the newborn Jesus. Titled “The Virgin and Child with a Flower on a grassy Bench,” it was last sold around 2016 in Concord, a Boston suburb.

The newspaper reports international art experts recently gathered at the British Museum in London to discuss the work.

Christof Metzger, chief curator at the Albertina Museum in Vienna, which houses a trove of Dürer’s works, told the Globe he has “absolutely no doubt” it is an original work from the German master dating to the early 1500s.

But Fritz Koreny, a former Albertina curator, suggests it likely the work of the artist’s star pupil, Hans Baldung Grien. Dürer, who died in 1528, was famed for his engravings and woodcuts.

The Globe reports the drawing is currently being offered for sale by Agnews Gallery in London.