Quarians

Nomads on a galactic scale, the Quarians are a people with no home. Forced into exile after losing their homeworld Rannoch and their colonies to their own Artificial Intelligence creations, the Geth, the quarians are born and spend their lives centered around the wellbeing of the Migrant Fleet. An amalgamation of whatever salvaged vessels they can scrounge up and repaired and overhauled variants of ancient ships, the Migrant Fleet is the wandering home of the scrappy species.

Rannoch held no natural insect species, and as such the quarians evolved in symbiosis with the natural flora of the world. As they became starbound and ventured from world to world, it was realized that this symbiosis, while strengthening them on their own planet, weakened their immune systems abroad. Forced to live in sterile environments aboard ships after their exile, the situation has only worsened. Quarians live within environmental suits almost all of their lives, only leaving in tightly-controlled environmental chambers or in the most desperate of circumstances.