This is a bulb platform. Built from chunks of planets, moons, or asteroids by the Jaavagi people and set into orbit around earth. Above the rock, is a bubbled city, that houses the oldest and most respected of each Jaavagi tribe. Inside the rock, exist a giganic hive, structure, previously built, before the colony ever takes flight from it's point of origin. Supermassive plants live inside of each bulb and run all kinds of resources through the colony, as well as improve the structural integrity and hold the rock together. The roots and limbs can be manipulated by the colony's oracle, who operates from just under the top of the outside dome. Each Orcle tower is different, though each colony must have a natural-born Jaavagi oracle to pilot it. The plants within, also store a sort of fiber-optic light and have figured out a way to slow change the physical form of light, making it a crystal, fog, or streaming liquid light. The entire colony, is a farmer of light, from their respective anchor star. As the Oracle looks into space, from inside the Oracle tower, under their star-dome, they can actually use the whole colony as a high powered eye to see through space. Though, the Oracle must be fully bonded with the supermassive plant through a series of implants behind the neck and into their own brain stem. Sharing life with one of the plants is a sure-fire way to go insane, lest you have the same genetic code as the previous Oracle. This let Oracles hand down their positions to offspring or exact clones.
Other vines are grown and are attached from place to place, then hollowed out, to work as tunnels for public transit around the colony's exterior.
For a view of the inside, just picture a spiral-staircase bee-hive with bridges that cross the massive, empty center. There is a main chord of the plant that runs down the entirety of this large open space, and it glows with the color of the colony's anchor star. This is light being caught by the plant and frozen into crystal form, within the transparent trunk. This provides all of the light for everyone inside the rock, in the undercity.
Lastly, the metalwork at the very bottom of the bulb is the only metal in the whole colony, besides that which is in the rock, or used inside the top city. These rails and beams are stuck into the rock to create a magnetic tether with the other colonies, a magnet slingshot, or anchor itself into an upright position. They are sed completely for magnetism purposes. It's their only way to move the whole structure, without an Oracle, or the help of gravity.