Endermite Infestations

In the End, there could be a chance for large, live colonies of Endermites to appear as rare structures with over- and underground elements, These would appear as branching burrows, not too dissimilar to ant nests in real life, and possibly incorporate End Cities as ruined structures, as if the Endermites have taken over such cities and forced the Endermen out.

The backstory around colonies may also link into how Endermites currently act, using teleportation by players/Endermen as a means to access and scavenge food. Colonies could also be home to new uniques which are worth players navigating many foes to reach. Challenge could be further increased by the addition of more formidable Endermite-related mobs in live colonies, akin to the Piglin Brute for Bastions.

These structures could be found across the whole end, however the introduction of a new biome in which this structure only spawns in may be a more interesting approach.