Rex Mason is an adventurer who is hired by Stagg Enterprises CEO, Simon Stagg, to retrieve a rare Egyptian artifact, the Orb of Ra. Shortly after hiring him, Simon Stagg learns that Mason has been dating his daughter, Sapphire Stagg. This and other incidents begin to fuel in Stagg a dislike for Mason that ultimately leads to a plot to kill him.
In an Egyptian pyramid, Rex Mason is knocked unconscious by Simon's brutish bodyguard Java and is eventually exposed to a radioactive meteorite from which the Orb of Ra was fashioned, transforming him into Metamorpho, the Element Man. He gains the ability to shapeshift and change himself into any element or combination of elements found in the human body.
Metamorpho has the ability to transmute his body into a wide variety of elemental compounds and form them at will. Originally, he was limited to elements that were naturally found in the human body. Somehow, this limitation seems to have disappeared. He can stretch, bounce, elongate, and reform himself like rubber or plastic. Rex is able to alter the consistences of these chemical elements and combines them into complex compounds. Metamorpho could reshape parts or the whole of his body. Rex's body provides him with natural armor, offering damage resistance from blunt and energy attacks. He is also a skilled martial artist, archaeologist, and detective.