Brick pyramid

Brick pyramids were tall experimental generated structures made up exclusively of bricks.

Generation
Brick pyramids would generate absolutely anywhere in the applicable versions, albeit rarely.

Structure
Brick pyramids were completely solid; they had no interior rooms. A strange quality about these pyramids is that if one dug under it, a layer of dirt and stone extended under the pyramid; they spawned right on top of the terrain instead of being a complete pyramid with the bottom underground (like with desert pyramids). The pyramid would generate its top block at the very top of the map, and would expand down from there, with each consecutive layer containing thhe next odd square number of brick blocks. Since the height limit at the time was 64 and sea level and typical ground level was 32, the base of a pyramid was usually 63 × 63 blocks and the pyramid itself was 32 blocks high. Whenever it spawned on top of a large body of water, it would usually add to the number of bases.