# Structures

NTM structure types and examples.

## Structure types

Each structure has a field reference and a generated example.

A structure in the `hbm` namespace tests `biomes` at the surface of its start column, whatever its type. Other namespaces use the vanilla test at the start position.

| Type | Placement |
| - | - |
| [`hbm:null_spawn`](https://movblock.mov/ntm-next/26.3/wiki/world-generation/structures/null_spawn.md) | Occupies a weighted structure-set choice with an empty placement. |
| [`hbm:features`](https://movblock.mov/ntm-next/26.3/wiki/world-generation/structures/features.md) | Generates NTM house, lab or silo components. |
| [`hbm:procedural`](https://movblock.mov/ntm-next/26.3/wiki/world-generation/structures/procedural.md) | Generates a procedural NTM structure at suitable surface terrain. |
| [`hbm:sellafield_crater`](https://movblock.mov/ntm-next/26.3/wiki/world-generation/structures/sellafield_crater.md) | Generates a Sellafield crater. |
| [`hbm:oil_bubble`](https://movblock.mov/ntm-next/26.3/wiki/world-generation/structures/oil_bubble.md) | Generates an underground oil bubble through structure-set placement. |
| [`hbm:bunker`](https://movblock.mov/ntm-next/26.3/wiki/world-generation/structures/bunker.md) | Generates a multi-room bunker. |
| [`hbm:jungle_dungeon`](https://movblock.mov/ntm-next/26.3/wiki/world-generation/structures/jungle_dungeon.md) | Generates a three-floor jungle dungeon. |
| [`hbm:ancient_tomb`](https://movblock.mov/ntm-next/26.3/wiki/world-generation/structures/ancient_tomb.md) | Generates an ancient tomb with spikes. |
| [`hbm:desert_atom`](https://movblock.mov/ntm-next/26.3/wiki/world-generation/structures/desert_atom.md) | Places the desert-atom structure template. |
| [`hbm:spaceship`](https://movblock.mov/ntm-next/26.3/wiki/world-generation/structures/spaceship.md) | Places the spaceship structure template. |
| [`hbm:single_piece`](https://movblock.mov/ntm-next/26.3/wiki/world-generation/structures/single_piece.md) | Places one selected template-pool element at terrain height. |
| [`hbm:legacy_jigsaw`](https://movblock.mov/ntm-next/26.3/wiki/world-generation/structures/legacy_jigsaw.md) | Assembles a jigsaw structure and grounds its pieces on terrain. |