Coalcats are living constructs built specifically for dangerous work in mines or in spaceports. They feed off of anything that burns by opening the hatch in their stomach and tossing it in, though coal seems to generally be the favorite food of choice. Due to their impervious nature and love of work their popularity caused their numbers to soar into the millions. Upset by the sudden lack of jobs the living meat beings put a ban on production of Coalcats roughly eighty years ago, hoping their numbers would dwindle through natural causes and various accidents.
Suffice it to say they did not, and in an effort to keep their jobs and their lives the Coalcats have formed their very own workers union and are now considered their own race, thanks to their efforts.