Threcaldian

Threcaldians (physiological classification TLTU) are a spacefaring extraterrestrial thermophilic species native to the planet Threcald V. They naturally thrive on temperatures around five hundred degrees; breathing superheated steam and using a hot liquid metal for blood. In addition, their gravity and pressure requirements are three times greater than those of oxygen-breathers. When outside their natural habitat, they use spherical, opaque structures, part spacesuit part vehicle. They are also one of the many member races of the Galactic Federation.

Appearances

 * Star Surgeon by James White
 * Major Operation by James White