The intact egg of a bird weighs half a ton.

When humans first arrived on the island of Madagascar about 1,500 years ago, they encountered a host of unique animals that would become extinct, including gorilla-sized lemurs, giant tortoises, tiny hippos and a long-necked, massive flightless bird that roamed the island's forests and laid the largest eggs of any vertebrate, including dinosaurs, according toSmithsonian.com.

The eggs of the Aepyornis, or elephant bird, were a valuable food source for the settlers of Madagascar. Weighing as much as 150 chicken eggs, a single elephant bird egg could feed several families. Humans plundered elephant bird nests, contributing to their extinction.

Today, very few of these bird eggs remain, with less than 40 preserved in museums. Therefore, staff at the Buffalo Museum of Science in New York, USA, were very excited to find an intact elephant bird egg among their large collection.

The Buffalo Museum of Science has amassed a collection over a century and is in the process of updating its catalog, with some exhibits listed only on cards and ledgers. While entering catalog data into the museum’s computer system, Paige Langle, zoology collections manager, opened a drawer that had not been viewed in a long time. Inside was a giant cream-colored egg. The egg was 12 inches long, 28 inches in circumference, and weighed more than 3 pounds. It was labeled a replica.

However, Langle was immediately skeptical because the egg looked too real to be a model. "I tried to lift it, but the more I looked at the surface of the eggshell and felt its weight, the more I thought it must be a real egg," Langle shared.

Langle was right. Digging deeper into the collections, Langle discovered a replica of an elephant bird egg that was actually a replica. Museum staff then looked in the archives and found records indicating that the museum had purchased a subfossil elephant bird egg from a London taxidermist in 1939. They also found a letter written by the museum’s curator at the time listing various items he wanted to purchase for his bird exhibition, including an elephant bird egg.

Museum staff sent the specimen to the University of New York at Buffalo for X-rays and examination. Conservation experts not only confirmed that the egg was real, but also that it had been fertilized. They were able to distinguish the yolk sac and noted the white patches that indicated a fledgling was forming.

Kathryn Leacock, director of the museum, hopes the new specimen will be useful to experts interested in elephant birds. There are several specimens of this large bird. The largest is three metres tall and weighs about 454 kg. Elephant birds became extinct relatively soon after humans arrived in Madagascar. The last elephant bird was seen in the 17th century./.