Believed to be more than 400 years old and nearly 200 times the size of a chicken egg, an extremely rare elephant bird egg will be auctioned in London this week, with an estimated price tag of up to $76,000. The egg, over 30 centimeters (11.81 inches) high, was laid by the now extinct elephant bird, a giant flightless bird indigenous to Madagascar, according to auction house Sotheby’s. The bird, believed to be the largest ever on earth at about three meters high and half a ton in weight, became extinct between the 13th and 17th centuries due to hunting. “It’s the largest egg from the largest bird that ever existed,” David Goldthorpe, senior director of Sotheby’s books and manuscripts department, told Reuters.