Rex Mason was an adventurer hired by Simon Stagg to retrieve a rare Egyptian artifact. After it was learned that Rex had been dating Stagg's daughter, Stagg began making a plot to kill him. In an Egyptian pyramid, Rex is knocked unconscious by one of Stagg's bodyguards, and exposed to a radioactive meteorite. This transforms Rex into Metamorpho, the Element Man. Metamorpho is one of many metamorphae, a race created by the Egyptian sun god Ra. With his abilities, Metamorpho can transform into any element, in solid, liquid and gas form.