Element Sigellian

Element Sigellian

While Superboy was imprisoned in Superboy Planet, a Superboy trophy explodes, launching an atomic chain reaction, releasing the element sigellian into the atmosphere, turning everything blue. This element is deadly to the Legion of Super-Heroes as kryptonite is to Superboy. Superboy releases a super-shout and changes the molecular structure of element sigellian, rending it harmless (Adv 267, Dec 1959: “Prisoner of Super-Heroes”).