Shark Bay, Australia
For about 85 percent of the history of life on Earth, only microbes existed. The only large-scale evidence of their activities is preserved by stromatolites, ancient structural records of life on Earth that hold evidence both of the biology of the microbial mat communities that created them and the nature of the environments in which they grew. They are rocky, dome-shaped structures formed in shallow water through the trapping of sedimentary grains by communities of microorganisms.
Yellowstone National Park
What is causing the beautiful colors in this hot spring in Yellowstone National Park? Life, that’s what! Many microorganisms live in the pools there, and because the temperatures of the springs are so hot (most are well over 100 degrees F, or 37.7 degrees C), they are called extremophiles (extreme-loving). They contain molecules that absorb the damaging rays of the sun, protecting their DNA. Those same molecules are also pigments that cause the different colors we see. Different extremophiles thrive in different temperatures, so the color of a particular area is determined by which organisms are living in it. A veritable rainbow appears as the water temperature decreases as it flows further and further away from its superheated source.
Mono Lake, California
Calcium carbonate formations called tufa give California’s Mono Lake an otherworldly feel. Mountains surround the lake, forming a closed hydrological basin—water flows in, but it doesn’t flow out. Because the only way for water to leave Mono Lake is through evaporation, it is naturally hypersaline—roughly two to three times saltier than the ocean. Freshwater streams and underwater springs have brought trace amounts of minerals into the lake over the eons, including arsenic. Recently, bacteria which appear to incorporate arsenic rather than phosphorus into their basic biological molecules were found living in Mono Lake
High Lakes, South America
The highest volcanic lakes in the world are located in the Andes Mountains of South America. Their elevation and isolation make them some of the least understood lakes on Earth and excellent analogs for lakes that existed on Mars 3.5 billion years ago. Simba Lake, at an elevation of 19,265 feet (5,872 meters) in the Chilean Andes, is red because of algae that developed pigments to protect themselves against high UV radiation. They float in the water near the surface, not deep enough to use the water column as a natural protection.
Pilbara, Western Australia
Created in a shallow pool on early Earth more than three billion years ago, these stromatolites represent a record of the most ancient life on Earth. They formed because colonies of microbes, as they grew, incorporated sediments from the water to create rocky structures. Found in Western Australia, the stromatolites take several different forms, including the slightly cone-shaped ones seen here resembling an egg carton. The structures shown in this picture are each about half an inch (1.2 centimeters) high.
Rio Tinto, Spain
Cloudy with particulates and flowing along terraces made of iron oxides, the Rio Tinto in southwestern Spain stretches for more than 62 miles (100 kilometers) before reaching the Atlantic. Despite its acidic waters and high concentrations of iron and other heavy metals, the river supports an incredible diversity of extremophile microorganisms, including algae and fungi. Microbial biofilms colonize the riverbed and are covered with yellow iron oxide precipitates, seen here. Because of geological similarities with Mars, the Mars Astrobiology Research and Technology Experiment (MARTE) team tested equipment at Rio Tinto in 2005 for drilling on Mars in search of subsurface life. 
Svalbard, Norway
Svalbard is a remote archipelago in northern Norway, deep within the Arctic Circle. Scientists with the Arctic Mars Analog Svalbard Expedition (AMASE) traveled there to test the protocols, procedures, and equipment needed to detect traces of organic chemistry and perhaps life on Mars. Instruments that will fly onboard NASA’s Mars Science Laboratory and ESA’s ExoMars missions were tested in Svalbard by the AMASE team. With a unique combination of volcanoes, hot springs, and permafrost, the Bockfjord Volcanic Complex on Svalbard is the only place on Earth with carbonate deposits identical to those found in the famous Martian meteorite ALH84001 (aka Allan Hills). 
Flinders Range, South Australia
Piece of upturned sandstone in the Flinders Range of South Australia shows ripple marks of an ancient sea bed. This area of Australia hosts fossils of the first complex, multicellular organisms, which began to emerge on Earth about 600 million years ago. The study of these early fossils, known as the Ediacaran Fauna.
Ellesmere Island, Canada
Borup Fiord Pass Glacier on Ellesmere Island in Nunavut is a site in the Canadian High Arctic where astrobiologists study the potential for life on Jupiter‘s moon Europa. Water rich in sulfur-containing compounds flows from the top of this 656-foot-thick (200-meter-thick) glacier, a chemical mix that is capable of supporting microbial life. Europa’s icy surface is similarly stained with sulfate salts.
