An extremophile is an organism that can live in extreme physical or geochemical conditions. Extremophile is a concatenation of from the Latin word, extremus, for ‘extreme’, and the Greek word, philiā, for ‘love’.
The word is relatively new. A search of Google’s Ngram viewer indicates the term starting showing up in published works starting in 1964:
Extremophiles are mainly microorganisms found in a variety of harsh environments around the world. Hot springs, ice caps, and thermal vents are just a few examples of extreme environments where extremophiles have adapted to live.
It’s these microorganisms that are responsible for the brilliant colors the line Grand Prismatic Spring, the largest hot spring in the United States and the third largest in the world. Found in Yellowstone National Park, the hot spring owes its brilliant colors thanks to microbial mats that line the mineral rich waters.
The extremophiles that thrive in Grand Prismatic Spring are known as thermophiles. Thermophiles can live in extremely hot environments at temperatures between 45–122 °C. The center of the hot spring is a deep blue color and is sterile due to the high heat. Each band of color is the result of a specific type of bacteria or algae.