This unassuming mushroom, Amanita phalloides, looks an awful lot like some safe, edible mushrooms—but one unfortunate collector discovered that it makes delicious but deadly soup. The fungus’s powerful toxin kills liver cells in a matter of hours. Amanita has been spreading in California since it was accidentally introduced from Europe in the 1930s. Scientists are trying to teach people to recognize them, and to and stop their spread.