Bryan Appleyard examines extremophiles – hyper-resilient organisms that may hold the key to new antibiotics, among other things:

Some estimates suggest that the biomass beneath the seabed is greater than that above. They have also encouraged a new confidence in the idea that we are not alone in the universe. The bandwidth of possible survivable environments—and, therefore, forms of life—has broadened enormously. … Extremophiles have changed our view of ourselves. We are, ultimately, their offspring.