A special fungus called Cladosporium cladosporioides, found living inside the roots of Gentiana yunnanensis (a traditional Chinese medicine herb), can tolerate extremely high levels of arsenic. Researchers discovered that this fungus protects itself from arsenic poisoning by storing arsenic mostly in its cell walls, converting toxic arsenic into less harmful forms, and activating its antioxidant defense systems. This discovery could help reduce arsenic contamination in medicinal herbs and lead to new methods for cleaning arsenic-polluted soil.