I roomed with a guy at a scientific conference who worked on thermophilic bacteriophage (viruses that infect thermophilic bacteria). Temporarily endowing bacteria with thought I could imagine them saying, "here I have this nice thermal vent around boiling point, acidic pH, no real predators can survive this horrible environment ... here come the phage. It seems that life will try to fill in any nook or crevice that is available.