Mushrooms have been dubbed world saviors as they could potentially clean up anything from oil spills to nuclear meltdowns. They are quite nutritious as well, however, 5% of mushrooms are toxic. While some mushrooms that are poisonous are brightly colored and easy to tell, most of the deadliest mushrooms have a relatively unexciting exterior. For example, one of the deadliest mushrooms in the world is called the Death Cap, and rightfully so as it’s earned its name by being responsible for the death of Roman emperor Claudius, Russian tsar, and a pope. It’s appearance it’s similar to several edible mushrooms.