The Ranel was a land-based species native to Peladine. They came in two flavors, one with grey skin, another with green skin. They looked like the aliens found at Roswell in the mid 20th century. The impoverished quarters of Ranel cities looked very much like late 20th century Earth slums, where Katola lived. (Star Trek: The Stoneship Files: "Educational Armageddon")