Aurigaen

The Aurigaens are a sapient non-humanoid species native to the planet Aurigae; the second world of their star system. Their biochemistry is not carbon-based, and they require extremely high temperatures to live.

Biology
Aurigaen bodies aren't carbon-based, and are instead based on a radioactive isotope of chromium, whose atomic weight is 52.9. This means that the Aurigaen themselves are radioactive. Thanks to their durable composition, their lifespan encompasses centuries.

The appearance of this species is unknown, although it's been mentioned that they don't have "hands" in the same way that Humans do. However, they do seem to have fingers, as it's been mentioned that their temperature is so hot that they couldn't possibly hold a sheet of paper with their fingers without damaging it. The temperature of their homeworld exceeds 500 degrees Fahrenheit (~ 260 °C).

In response to a Human who imaged them as being chunky, metallic-looking beings, an Aurigaen assured that they look nothing like that, but their actual appearance is still left undescribed.

Appearances

 * "Dear Pen Pal", by A. E. van Vogt (1949)