Mushroom Pool, in the Lower Geyser Basin of Yellowstone National Park. The pool

Mushroom Pool, in the Lower Geyser Basin of Yellowstone National Park, as it looked in June 23, 1967. The sample that would be the source of Thermus aquaticus strain YT-1 came from this hot spring. Pictured is Thomas Brock standing near the edge of the pool. Image from the self-published "A Scientist in Yellowstone National Park" (Brock, 2017).