Argolin

The Argolins are a sapient humanoid species from the planet Argolis, which was devastated in a brutal (though not unprovoked) attack by the Foamasi, turning their world into a radioactive wasteland and forcing the remained Argolins to spend their lives confined within sealed underground cities.

Biology
They appear like Humans with pale greenish or yellowish skin, and hair patterned in shades of green and yellow. On the top of their heads there are several pebble-like nodules, which will fall down one by one as the Argolin ages. When the last nodule falls the Argolin's body will deteriorate in a matter of seconds, killing them immediately. This strange metabolism was actually one of the consequences of the devastating radioactive warfare that fell on their planet, with another one being that they are irreversibly sterile, and therefore face danger of extinction.

Appearances

 * Doctor Who, season 18, The Leisure Hive (1980)