Microbes that thrive in extreme environments are known as extremophiles. These organisms have adapted to survive and often thrive in conditions that would be lethal to most other life forms.

Here are some examples of extremophiles and the types of extreme environments they inhabit:

As for the ecosystem that covers the largest area of Earth's surface, that would be the marine ecosystem, specifically the world's oceans. Oceans cover approximately 71% of the Earth's surface, making them the largest biome on the planet. These vast marine ecosystems support an incredibly diverse range of life forms, from the smallest plankton to the largest whales. They are critical to the Earth's climate regulation, carbon cycling, and provide a source of food and livelihood for billions of people. The marine ecosystem is subdivided into various zones, including the pelagic zone (open water), benthic zone (ocean floor), and various coastal ecosystems, each with its own unique characteristics and habitats.

Dr Gaurav H Tandon thank you for your contribution to the discussion

Extremophiles are group of microorganisms that possess ability to tolerate and live under the extremes of physico-chemical, geological and nutritional conditions. Extreme environments include the geographical poles, very arid deserts, volcanoes, deep ocean trenches, upper atmosphere, outer space, and the environments of every planet in the Solar System except the Earth. The World Ocean is the largest existing ecosystem on our planet. Covering over 71% of the Earth's surface, it's a source of livelihood for over 3 billion people. Marine waters cover more than 70% of the surface of the Earth and account for more than 97% of Earth's water supply and 90% of habitable space on Earth. Seawater has an average salinity of 35 parts per thousand of water. Actual salinity varies among different marine ecosystems. Freshwater ecosystems cover less than 1% of Earth's surface, yet are home to at least 10% of Earth's species. The aquatic biome is the largest of all the biomes, covering about 75 percent of Earth's surface. This biome is usually divided into two categories: freshwater and marine. The ocean is a huge body of saltwater that covers about 71 percent of Earth's surface. The planet has one global ocean, though oceanographers and the countries of the world have traditionally divided it into four distinct regions: the Pacific, Atlantic, Indian, and Arctic oceans.Forest ecosystem: being a very large area of forest, it can support a huge life and ecosystem of different species of plants and animals. It covers up to 70% of the total ecosystem. Biosphere is the sum of all and hence regarded as the largest ecosystem of the earth. Biosphere is the regions of the surface, atmosphere, and hydrosphere of the earth (or analogous parts of other planets) occupied by living organisms. The most extreme extremophile that is known at the moment is the Deinococcus radiodurans. This microbe can survive extreme cold, drought, thin air and acid. It has even been found on the walls inside nuclear reactors, where the radioactivity would be instantly fatal for humans. These include viruses, bacteria, fungi, protozoa, and microbial metabolites. Original photographs of all the main groups of microorganisms are presented using light and electron microscopy. Major classes of extreme environments encompass acidic (pH < 5), alkaline (pH > 9), hypersaline (salinity > 35‰), pressurized (> 0.1 MPa), hot (> 40°C), cold (