"The composition was unique. There's nothing like it on Earth, with one exception: The meteor rocks found here in Smallville. So I have fashioned my own key. It's identical in every detail." – Lionel Luthor, to Clark Kent, Exodus The kryptonite key, identical to the Key, was created by Lionel Luthor to put into the keyhole in the cave wall inside the Kawatche Caves. He created it out of kryptonite because, as he explained to Clark Kent, the original key was made out of a metal alloy close in composition to the meteor fragments.