Mars, the Red Planet, Earth's Sister Planet. Once believed to be a world much like our own, now its a barren wasteland of rocky hills and frozen deserts. It was a natural choice for both early Human Colonization and the use of early terraforming technologies. While the Planet isn't fully terraformed, It still harbors the second largest human population in the Sol system, over 7 Billion Humans call Mars home, earning themselves the name Martians.
Mars was the home of the revolution during The Colony Wars, where the Martian Militia was formed and Humanity fought the Global Incorporate as a united force.
Mars is covered in frozen deserts, with towering rocky hills and vast treks of barren desert. As Human Colonization and Terraforming continue on the planet, the temperature is expected to climb to become similar to Earths, which would allow more varietys of plant and animal life to live on the Red Planet.
Its sand is a red color because of the iron oxide concentration within the soil, to the point that prolonged exposure to the sand in early childhood can "Stain" the person's skin light red, with coined the term 'Martians' for Humans born on Mars.
Mars Ice Caps are vital for the mass production of Hydrogen fuel for space craft, and its vast quantity of Iron buried under the dunes has been a constant source of usable material for various industry, to Martian made weapons, vehicles, surgical tools, and various more.
Flora & Fauna
While native species on Mars died out a Millennia ago, Animals Imported from Earth now thrive in the terraformed atmosphere, for instance Elk live on the frozen poles. Flora is rare and far between on Mars due to its constant cold temperatures, but as terraforming continues on the planet, more and more floral species are likely to grow.
In Regards to extinct species on Mars, sections of mars have been declared "Fossil Preserves" where palotologists scower the Martian landscape for fossils. While nothing larger than microbiology has been discovered, their are hopes as they dig deeper they will find larger creatures.