 Maggin contains descriptions of Krypton, mainly referencing the Silver Age version; it describes the planet as a "failed star" with massive surface gravity and extremely hostile, glaciated conditions, which forced extreme adaptation and rapid evolution in the descendants of humanoid space travelers (and their dogs) who became stranded on its surface in prehistory.This led to an extremely strong, dense, and durable Kryptonian species with unusual physical properties.Maggin describes the rise of a civilization which uses geothermal heat as its primary power source, developing science and technology, but finding it difficult to escape the massive world's gravity.