The Mirror

A mythic zone. The land hangs upside down from the sky.

The Mirror is a zone type in the Overworld. The zone's own land hangs upside down from the top of the world, over the real land.

What it looks like

Every column of land has its copy in the sky, flipped. A hill hangs down as a hill. A valley is a dip in the underside.
Trees hang roots up, with their crowns at the bottom.
The copy's top is flat, right under the build limit. Its underside is the surface of the land, upside down.
Seas, rivers and lakes are not copied. Where they are, the copy hangs with empty beds. Ice is left out too.
Lava hangs as magma. Gravel is cobblestone. Packed ice is clay. In deserts sand is sandstone, and in badlands red sand is red sandstone. Elsewhere sand is left out.
Grass blocks are left out, so the dirt under them shows, as it would under any block.
From below it is a second world over your head. From the side it is a slab of land floating in the sky, cut off where the zone ends.

The copy never touches the ground. Over mountains, where the hanging land would come down too low, it is cut off flat high over the peaks.

What is in it

Nothing in it falls and nothing flows. Leaves never decay.
There is no ore. Ore blocks are left out, so the copy has gaps where they were.
Chests, spawners, beds, beehives and the like are not copied. Neither are flowers, grass, torches, doors and other small things that need a block under them.
Buildings and ruins hang upside down too, without their loot.
Every block in it is one the land under it already has, or a swap that the biome makes on its own.

Under it

Over land, the copy shuts out the sky. The ground under it is dark, and monsters spawn there day and night.
The ground itself is ordinary land, with its trees and plants.

How rare it is

The Mirror is a mythic zone, rarer than any legendary one. About 0.01 percent of zones are Mirrors, about one zone in 10,000. It exists in the Overworld only, and only in land far from anything that existed when it was added. The land around spawn never gets it, so go far.

There are no other chunk errors inside the zone.

See Chunk errors for every zone type, and Exploring for how finds are logged.