They are powerful, winged creatures which have a multitude of fleshy tendrils streaming from their undersides. It is these tendrils that allow an Oswaft to manipulate objects. Normal adults are known to reach lengths of 750 meters or more, while the Elders can grow to 1,000 meters. They have strange, transparent flesh, inside of which can be seen the colors and sparks of chemical reactions. It is believed that some two-thirds of their body mass is used as their brain. When an Oswaft dies, their flesh becomes opaque, and eventually decomposes into its molecular components.
Oswaft can communicate across vast distances almost instantly by modulating radio waves to form complex strings of images and concepts, and they have developed a way to manipulate microwaves to enter hyperspace by themselves. This allows them to "skip" anywhere in an instant, although the nature of the Oswaft society is to stay at home in the StarCave, where they can avoid the dangers of what they called the Open Sea of space. They are incredibly intelligent, but have only gained knowledge within the confines of the StarCave. Thus, they are unimaginative beings with incredibly long lifespans, and their society is steeped in conservative traditions. They are virtually immune to fear, and never panic. The Oswaft have the ability to synthesize complex molecular structures, provided that they have the raw atomic material to start with. The Oswaft society is ruled by a group of Elders, and is believed to have numbered in the billions, all living inside the ThonBoka.
When Emperor Palpatine learned of the existence of the Oswaft, he believed that huge, sentient creatures which could move through hyperspace without starships were a threat to the Empire, and ordered them eradicated. Imperial forces blockaded the mouth of the StarCave nebula, regularly issuing poisonous discharges to kill the pre-organic motes that float into the ThonBoka and provide sustenance to the lifeforms inside. Lando Calrissian eventually talked the Oswaft into fighting for the ThonBoka, and together they broke the Imperial blockade and freed the Oswaft.