But as the quarians gradually modified the geth to do more complex tasks, developing a sophisticated neural network, these changes altered the geth to such an extent that they became sentient. The quarians kept their programming as limited as that of any VI, nothing close to an AI, remaining mindful of the Citadel Council's laws against artificial intelligence. They created the geth around the late 1850s CE to be used as labourers and tools of war. Hailing from the world of Rannoch, the quarians were always a technologically capable species. Another endures traveling through multiple racial environments without a suit, dealing with things like elcor high gravity and drell aridity before dying in the high-pressure volus zone after a considerable amount of time there. One extensively tortured quarian survives for a while without an enviro-suit before dying from his injuries. Grunt's tank imprints specifically deem several species soft and easy to kill, but not quarians. Other than the oft-mentioned maladjusted immune systems, the quarians have surprisingly robust physiology. Quarians who want to taste something (other than the refined edible paste issued to all who leave on their Pilgrimage) can eat specially purified turian cuisine, though the typical quarian diet is vegan, as livestock were found to possess an inefficient resource-to-calorie ratio when stored on the Migrant Fleet. The food of levo-protein races such as humans or asari is at best inedible and at worst poisonous, most likely triggering a dangerous allergic reaction. Like turians, the quarians are a dextro-protein species of reverse chirality from humans and asari. However, doing so guarantees a quarian will get sick, although they will usually adapt over time.

The most intimate thing quarians can do is link their suit environments. Ships in the Migrant Fleet often contain 'clean rooms' where quarians can give birth or undergo medical procedures in relative safety, though there are always risks.

As a result, physical acts of affection are difficult for quarians, even for the purposes of reproduction. However, they prefer the safety of their suits even in clean environments and are reluctant to remove them without a good reason.ДЄ quarian who wishes to remove their suit must take antibiotics, immuno-boosters, herbal supplements, or the like in order to do so safely, and even then there are inherent risks. As such, quarians are given various vaccinations and immunizations to help ward off disease. After living aboard the Migrant Fleet for generations, the quarians' immune systems have atrophied further still due to the years in the sterile environment of the Migrant Fleet. Furthermore, what few viruses and other microbes were native to their homeworld were often at least partly beneficial to them, giving them a symbiotic relationship with their environment. Quarian immune systems have always been relatively weak, as pathogenic microbes were comparatively rare in their homeworld's biosphere. A quarian's lifespan is roughly equal to a human's, but is prone to be less if infection breaks into the suit. Along with their suits, quarians also have extensive cybernetic augmentations integrated into their bodies. 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). As a result, all quarians by necessity dress in highly sophisticated enviro-suits, to protect them from disease or infection if they are injured. The most distinguishing feature of quarian biology is their weak immune system, compounded by centuries of living in sterile environments.

Male quarians, however, appear to lack a third toe. Aside from hands and legs, their general body shape and sexual dimorphism is similar to humans. Their lower legs are bowed backwards significantly, compared to asari or humans. They also have three thick fingers on both hands which include a thumb, an index finger, and a long finger, similar to the middle fingers for humans, as well as three toes on each foot. Quarian facial structure and hair actually makes them the most similar to humans in physical appearance. Their eyes can see into the ultraviolet end of the spectrum their suit HUDs can show information in those wavelengths. Their ears or ear analogues differ in a noticeable fashion from those of humans, with references made to 'what for the quarian version of an ear'. Quarians have an endoskeleton, lips, teeth, and two eyes with eyelids and tear ducts. Quarians are generally shorter and of slighter build than humans.

Mass effect 1 quarian armor