Researchers discovered that the medicinal fungus Poria cocos creates its own specialized microbial environment in its underground structure that is closely linked to the production of pachymic acid, a compound with anti-cancer and immune-boosting properties. By comparing the microbes living in the fungus versus surrounding soil, they found specific beneficial bacteria and fungi that thrive in the fungus but are rare in soil. This discovery could help improve cultivation techniques to produce higher quality medicinal fungi with more therapeutic compounds.