Byllura IX is the farthest planet from the sun, which makes it the coldest in the system. Its distance to the sun is almost twice that of its closest neighbor, Byllura VII. At first, it was thought that Byllura IX could have originated when a comet or an asteroid was trapped around the orbit of the star. However, the relatively large size of the planet and the remarkable volcanic activity, rarely seen in asteroids and comets, disproved this theory.
Traces of sulphur oxides make the atmosphere slightly toxic and the absence of oxygen make it unbreathable to most lifeforms. Water is also a minor component of the atmosphere, but there is a large amount of ice in the northern pole. Due to the extreme axial tilt, this hemisphere is in perpetual darkness, being colder than southern hemisphere. There are two main volcanic areas, one on each side of the equator. The rest of the world is mostly barren rocks tortured by constant winds, The winds have resulted in dust storms being common throughout the whole planet. Some of them even form visible spots on the surface, but none last longer than a day.
As seen in most planets, initial colonization attempts on Byllura IX were related to mining. There are tales from the early mining settlements, tales about the caves on the planet's surface. It is said that deep inside these caves there is breathable air and maybe something else. Are the caves an entry door to an inner world? No one has dared to venture deep enough to find out.
The most famous tale states that one of those pioneers was caught by a storm while prospecting and sought refuge in the caves. As the storm seemed long-lasting, he ventured deeper inside the cave. According to his last communications, he had a problem with his breathing equipment and he took it out, only to find that he could breath in the cave. He kept in contact with his HQ for several hours, but after that contact was lost and the rescue team was unable to find him or any traces of his equipment. Some say he was robbed by a rival mining corporation, but dreamers wonder if he managed to reach the hypothetical underworld. It is also said that every year, his widow leaves a rose at his last known position.