A gigantic egg from a massive extinct bird that was sitting in a storage area at a New York museum unbeknownst to scientists is now receiving more recognition.

The foot-long egg from an elephant bird is fully intact and weighs three pounds, 5 ounces, the Buffalo Museum of Science said in a statement. It was “mislabeled as a model due to the rarity of this type of egg,” but the error was discovered as staffers were doing a fresh inventory and catalog of its pieces.

“Lost, hidden or misidentified artifacts and specimens are not uncommon in museums that have been collecting for centuries, and we are thrilled to rediscover this rare egg in our collection,” Director of Collections Kathryn Leacock said in the museum statement. “The Buffalo Society of Natural Sciences has been collecting since 1861, and as we continue to care for the collection, there is always more to learn and discover.”

As the museum explained, “cast eggs are commonplace in museum collections,” so the team reached out to experts who radiographed the specimen to confirm its authenticity.

“Further investigation into the archival record revealed the egg was purchased from Edward Gerrard & Sons of London in 1939,” according to the museum statement.

That firm included people who were taxidermists, made anatomical models and dealt in artifacts particularly from the Pacific area.

Elephant birds were about 10 feet tall and weighed close to 1,000 pounds. Their massive eggs were the equivalent of several dozen chicken eggs and they may have gotten their common name from their broad legs.

The flightless bird species, which was found in Madagascar, went extinct hundreds of years ago, although when exactly that happened has been the subject of some debate. Some put the last recorded elephant bird sighting at a point in the 1600s.

They may have died out from a combination of factors, including environmental changes and humans poaching their eggs.

The Buffalo museum bills its newly discovered historical specimen as “one of the largest eggs ever laid by a vertebrate animal.” It is making its debut on May 1 as part of the museum’s Rethink Extinct exhibit.

There are fewer than 40 intact elephant bird eggs in public institutions around the world, the museum said.