Sail Into the Light
The Skinborne are rarely seen by Ein Soph's inhabitants - they eschew the worldship's internals to cling to its metal Skin, safe from the threats of that inner world. The rare times they breach the Skin, it's for sudden, violent raids that gather as many resources as they can in the space of hours.
Their technology is incredibly advanced - not only do they have spaceflight, hydrogen from Ein Soph is harvested to power generators and weapons far beyond what the Navigator Houses have achieved.
They live nomadically, drifting across the Skin in small voidcraft. These crews stay on their voidcraft for months at a time; despite this, they are nearly empty, with no frivolous items onboard except for a single seemingly random object in each person's quarters, kept atop an altar. Once their voyages are complete, they return to the Ark to refuel.
They are confused by the other societies of Ein Soph - can they not see they are failing their test? How do they expect to leave this hateful place when the Garden World arrives?
Their Exodus
According to their religion, Ein Soph is the Iron World, a test from a stern, silent god. Every ten thousand years, this Iron World passes by the Garden World, a paradise of nature and abundance.
But the Iron World never reaches it. Even at its closest point, they are millions of miles away. This is the test their god has given them - to escape. The vessels they use to skip across the Skin like a stone over water are children's toys compared to their true project - a city-sized starship pointed out from Ein Soph, into the void.
Soon, they say, they will escape this world forever.
Their Ancestors
The Iron World's orbits have gone on since the beginning of time - entire generations of people have escaped from its grasp, and passed their test. The spirits of these ancestors are revered, and their knowledge is treasured and collected into the Skinborne's holy books - somewhere between Bible and technical manual.These ancestor spirits are spoken to through objects, passed down through generations and once owned by the spirit in question.
Their Ark
An entire engine of Ein Soph, uncountable stories high, slowly turned to face at a shallow angle. Titanic battery banks, leeching power from the worldship to keep this parasite alive. The Ark is the culmination of generations of work - the answer to the test the Skinborne have been given. Now they wait, until the Garden World comes into view and they can sail away into the light.