End spike

End spikes, also known as obsidian spikes, obsidian pillars, or obsidian towers, are generated structures in the End that are made of obsidian.

Generation
End spikes generate naturally the first time the player enters the End, and regenerate when the ender dragon is respawned.

If the End biome is used in the overworld, End spikes generates without bedrock and end crystals, only obsidian, with some of them containing iron bars. End spikes generate near coordinates 0,0. If the terrain is high enough, End spikes can generate buried or inside caverns but generates air blocks around and on top of it. If End biomes generate next to other biomes near 0,0 only some End spikes generate.

When the ender dragon respawns, any blocks the player had placed are deleted within a 10 block radius of the bedrock block at the top of the end spikes.

Structure
End spikes are composed of obsidian, with a single bedrock block and an end crystal on top of each pillar. They have circular forms.

The following 10 pillars generate in a 43-block radius circle around the exit portal in a random order (total of 40499 obsidian):
 * A 3-block radius pillar ending at y=76 (total of 1596 blocks of obsidian);
 * A 3-block radius pillar with iron bars ending at y=79 (total of 1659 blocks of obsidian);
 * A 3-block radius pillar with iron bars ending at y=82 (total of 1722 blocks of obsidian);
 * A 4-block radius pillar ending at y=85 (total of 3145 blocks of obsidian);
 * A 4-block radius pillar ending at y=88 (total of 3256 blocks of obsidian);
 * A 4-block radius pillar ending at y=91 (total of 3367 blocks of obsidian);
 * A 5-block radius pillar ending at y=94 (total of 5358 blocks of obsidian);
 * A 5-block radius pillar ending at y=97 (total of 5529 blocks of obsidian);
 * A 5-block radius pillar ending at y=100 (total of 5700 blocks of obsidian);
 * A 6-block radius pillar ending at y=103 (total of 9167 blocks of obsidian).

The bottom of all pillars are at Y level 0, which means that pillars are generated through the island.

The second and third shortest pillars include a cage comprised of 73 iron bars surrounding the end crystal, to protect it from projectiles.

Trivia
The obisidan pillar is one of the six ways for bedrock to naturally spawn, including the bottom of the Overworld, the End Gateways, the bottom of the Nether, the top of the Nether, the top of the obsidian pillars in the End, and the Exit Portal.