The Bolovax were an alien species. Its best known member was Kilowog. Bolovax physiology was noted as being somewhat similar to that of a Martian, similar enough that J'onn was able to treat Kilowog's injuries. However, they are different enough to necessitate a significant amount of guesswork on J'onn's part while adjusting the Watchtower's medical equipment to treat him.
J'onn J'onzz refers to Kilowog as possessing a "Bolovax physiology", obviously in reference to Kilowog's home planet in the comics, Bolovax Vik.