A Japanese research team has concluded that an iron dagger made of meteorites found in the tomb of Egyptian pharaoh Tutankhamun was forged at temperatures of about 950 degrees or lower.

A decade after jihadists ransacked Iraq’s famed Nimrud site, archaeologists have been painstakingly putting together its ancient treasures, shattered into tens of thousands of tiny fragments.

Their examination of the dagger revealed that the artifact is more extraordinary than it might have initially appeared. The primary enigma was the uniform blade of steel, composed of iron with ...