Navalny, a Russian anti-corruption activist and well-known critic of President Vladimir Putin, is being treated in Germany for an apparent case of poisoning by an "organophosphorus neurotoxin." But which one: the insecticide or the chemical weapon? Here are some clues.
Lake Okeechobee, in South Florida, is being plagued by an enormous algae bloom. But what's causing the problem is not algae: it's a plant-like pathogen called cyanobacteria. Blooms from this type of bacteria are dangerous because they release a variety of deadly neurotoxins, which can kill humans and animals.