Chernobyl fungus could shield astronauts from cosmic radiation

"Extrapolating these results, the researchers estimated that a roughly 8-inch layer of C. sphaerospermum "could largely negate the annual dose-equivalent of the radiation environment on the surface of Mars." That would be a significant benefit to astronauts. After all, an astronaut who is one year into a Mars mission would have been exposed to roughly 66 times more radiation than the average person on Earth."

https://bigthink.com/surprising-science/radiation-on-mars-fungus