The Martian wanal or ock-croc was the only large predator left on Mars at the time of Mac Stone. These giant, tentacled reptilian insects drove deep burrows using old blowholes or wells; they weren’t particular. They hibernated for years, woke up very hungry. The first hatchling typically ate all its siblings and sometimes its parent. Then it ate whoever was still hibernating. Although not radioactive themselves, they preferred areas still “buzzy” and lethal to humans.