Quarian

The quarians are a nomadic species of humanoid aliens known for their skills with technology and synthetic intelligence. Since their homeworld Rannoch was conquered, the quarians live aboard the Migrant Fleet, a huge collection of starships that travel as a single fleet. Approximately three hundred years ago the quarians created the geth, a species of rudimentary artificial intelligences, to serve as an efficient source of manual labor. However, when the geth gradually became sentient, the quarians became terrified of possible consequences and tried to destroy their creations. The geth won the resulting war and forced their creators into exile. Now the quarians wander the galaxy in a flotilla of salvaged ships, secondhand vessels, and recycled technology. The most important fact of quarian biology is their weak immune system, compounded by centuries of living in sterile environments. As a result, all quarians by necessity dress in highly sophisticated enviro-suits, to protect them from disease or infection if they are injured. Their suits can be compartmentalized in the event of a tear or similar breach to prevent the spread of contaminants (similar to a ship sealing off bulkheads in the event of a hull breach). A quarian's coming of age ceremony is a Pilgrimage in which they go out into the universe to bring something back of use to the fleet and learn perspective about their lives. Quarians are used to cramped conditions in which everyone relies on everyone else, and because of this, contrary to stereotypes, quarians are an altruistic people that value family and crew.