I am trying to justify a fungal life-form that lives in an alternate version of the Kuiper Belt. The life-form is (loosely) based off of this article: https://www.zmescience.com/science/geology/fungus-eating-minerals/
The spores of my life-form are cast into space in all directions, and those that land on an asteroid (a very small number) composed of necessary materials (iron, water ice and oxygen) will consume those materials, tunneling through the asteroid as they do so. Extremely low temperatures would cause this process to last for thousands of years.
Eventually, they create a maze of tunnels and pits throughout the asteroid, similarly to the kind detailed in the article. As the life-form spreads and expands through the tunnels, it generates large "caps" (like mushrooms) responsible for releasing more dormant spores, which drift through the tunnels out into space until they land on another asteroid. As a result, by the time of my story, the life-form has spread through most of the asteroid belt. Once the caps have released their spores, they die, but without an atmosphere, they do not decompose, remaining planted in the tunnels of the asteroid.
Could this general concept work? Obviously, life in a vacuum is harsh, and radical temperature changes and radiation would be constant; however, I was under the impression that some fungi (like mold) can survive such conditions.