"[Melanin] doesn't reflect any light; it's all going into it. Is it all disappearing into a black pigment and has no use whatsoever? Biology is incredibly inventive," Casadevall argues. After all, extremophile microbes thrive in the heat and acid of hydrothermal vents below the sea or live off the radiation of decaying radioactive rocks deep inside Earth's crust. "It's not that outlandish," Casadevall says, for fungi to harvest the energy in ionizing radiation with the help of melanin. But it is unexpected and strange.