The end of this excellent answer lead me to Wikipedia which linked to The blacker the better… especially in Chernobyl and Chernobyl Fungus Feeds On Radiation. One passage in 'blacker the better' caught my eye:
Melanized fungi actually seem to thrive in environments with high levels of ionizing radiation (ultraviolet, x and gamma rays), which is usually seen as very dangerous to life.
And then it goes on:
The walls of the damaged nuclear reactor of Chernobyl are covered in melanized fungi and they also are found living very happy on board of the International Space Station. Experiments showed that these melanized species of fungi seem to benefit from radiation, increasing their growth and germination.
Melanized fungi seem to be fungi which can produce a form of melanin, which may be able to derive some biological advantage (energy for synthesis or metabolism perhaps) from light or even radiation.
Have melanized fungi been found happy on the ISS? Is there anything written about this I could read? Any idea if they are gaining some biological advantage from higher radiation levels there? Were they there intentionally (part of an experiment) or did did they travel as common contamination or spores from Earth?