Don't forget about extremophiles. They live in areas that people say are impossible. Some microbes even live in radioactive waste. And some extremophile mushrooms even live on the radioactive remains of Chernobyl. There are are organisms that "breath" toxic gasses living in caves, and they're not microbes, they're small animals. They're also sightless because the eyes are not necessary in those caverns. Yet we always maintained that life was impossible in those environments due to the intense heat / cold / toxicity levels. So, seeing one where H2O is toxic? Quite possible.