Upside-down biomes in the nether

The Nether would lend itself well to having upside-down biomes, since it has an empty ceiling everywhere. I would assume some kind of corrupted fungi is responsible for this—perhaps a variant of the warped or crimson fungi. These biomes could feature mobs walking on the ceiling, upside-down vegetation, mushrooms, and more. Blocks unique to these biomes—such as fences or chests crafted from their wood—could also appear naturally flipped upside down.

There could also be an ancient upside-down structure overtaken by this fungus which, once defeated, would reward the player with a rare item or block that grants temporary inversion. This mechanic could unlock a lot of creative building possibilities, add a new way to traverse the Nether, and introduce an interesting twist to the dimension.