Beneath the surface of what we dismiss as spoilage and contamination, nature has been quietly engineering resilience. Researchers have found that Mucor racemosus, a fungus already living in the human gut and present in fermented foods, can measurably protect mice from radiation damage — not by resisting harm, but by helping the body remember how to heal itself. Published in PNAS, the findings invite a broader reckoning with how much of our biological protection may already reside in organisms we have long overlooked.