A common edible mushroom called A. crocodilinus can accumulate dangerous levels of cadmium from soil without being harmed. Scientists discovered this mushroom produces two different proteins called metallothioneins that work together to safely trap and store the toxic cadmium. One protein handles constant, everyday cadmium storage in the mushroom fruiting body, while the other activates quickly when the roots encounter sudden heavy metal stress. This same protective strategy appears in other mushroom species, showing it’s an important evolutionary adaptation.