An Omnistructure because it is not just a structure filling reality, but a structure that is reality. A reality that can only exist as structure, in the same way that ours is expressed as space and form.
Here are worlds the size of Nebulae, grown, not in tight massed spheres and gravity wells, but like ferns or fractal fungi infiltrating a mass. Storm-wrapped tendril worlds with neutronium cores. Worlds as slender as mycelium, all linked, receiving their light from the transient civilisation of intelligent nomadic suns. Primary trunks of world with surfaces like gas giants and storms as large as small galaxies.
Entire world-equivalent biospheres spending their existence transiting and slowly evolving. Sometimes running into each other, resulting in titanic conflicts and strange syntheses.
Gravatically balanced structures of form. Vast tendrils of world.
Some worlds with hollow cores like old trees, some wormed within by passages and cells, some carrying lightless life inside.
Some oceanic, like branches of water. Some carrying vast globular oceans at their tips. Sometimes these oceans have frozen surfaces and pressure-ice cores. Sometimes they break free and drift, are caught and smeared through the Lagrange zones causing disaster and opportunity.
Sadly, all the world curls have fallen into decay. They are blackened and dying, though the diamond highways sing.
The highways are cylinders the thickness of stars, transparent, flexible diamond lattice environments, home to their own intelligence yet transmitting a blood supply of light.
At the nexus-points of the intersecting highways, like the cores of neural cells, are the Photo-Arcologies , gigantic hives of living suns that take on strange insectoid forms. Between the worlds the suns are harmonies of light like freight trains spiralling round the helices inside the diamond highways.
Yet without the responsive song of life from the the world fronds, the arcologies themselves grow silent, the highways are failing, slowly but inevitably being cut off. Eventually the culture of the Omnistructure will retreat, becoming only a memory. In the star-cemeteries deep in the centres of the Photo-Arcologies, black-hole tendrils and white dwarf root-stubs animate and attempt escape.
The space between the highways and the mycellium of world is divided into cells of void, like the cells of a leaf, each similar but distinct. At the border of each cause/effect lipid layer, time hesitates for a moment to confirm.
Lagrange points within the cellular voids play host to their own strange zero-g civilisations. High altitude web cities grow like gigantic highway shacks along the easy-to-transport zero-g lines between the world-roots and the suns.
Lagrange points generally lie at the borders of void cells and have slightly different realities depending on which side you are on. Multi-cell Lagrange strands are complex, with many realities involved. They say if you agree something there you must agree it four times, once between all possible combination of yourself and the other party.