# hbm:single_piece

Places one selected template-pool element at terrain height.

Vanilla structure settings follow the [Minecraft data pack format](https://minecraft.wiki/w/Data_pack).

## Fields

| Field | Meaning and default | Range |
| - | - | - |
| `type` | Selects the structure implementation. | |
| `biomes` | Vanilla biome set eligible for placement. | |
| `height_offset` | Y offset applied after averaging terrain across the rotated footprint. | `i32` |
| `min_height` (Optional) | Lower bound for the clamped average-ground height; default 1. | `i32` |
| `max_height` (Optional) | Upper bound for the clamped average-ground height; default 128. Must be at least `min_height`. | `i32` |
| `spawn_overrides` | Vanilla mob-spawn overrides inside the structure. | |
| `start_pool` | Template pool from which the single piece is selected. | |
| `step` | Vanilla generation step for the structure. | |
| `aquatic` (Optional) | When false, refuses a start whose footprint has a corner with ocean-floor height below sea level; default false. | |

## Example:

Source path: `data/hbm/worldgen/structure/aircraft_carrier.json`

```json
{
  "type": "hbm:single_piece",
  "biomes": "#c:is_ocean",
  "aquatic": true,
  "height_offset": -6,
  "max_height": 42,
  "spawn_overrides": {},
  "start_pool": "hbm:single/aircraft_carrier",
  "step": "strongholds"
}
```