Asteromorphian "Hyper-Augmented Hollow Asteroid" (H.A.H.A)

In order to hide from the Qu, Asteromorphs hollowed out asteroids and installed nuclear engines on their sides, building stealthy interestellar arcs out of them. Once the Qu left, the need for more space pushed the Asteromorphs into expanding their bases by adding extra layers to the hollow asteroids. No longer needing to hide, those layers eventually reached the surface. With time, only small portions of the original asteroid remained, usually in the form of small terraformed domed gardens.

The third and forth picture depict the arc travelling, and reaching a near star, with the intention of replenishing its fuel.

Based on "All Tomorrows: A Billion Year Chronicle of the Myriad Species and Mixed Fortunes of Man" by C. M. Kosemen.
The background sun image used in the forth render was taken by u/ajamesmccarthy.