There is a vast variety of structures that can generate in Minecraft. Minecraft has many different naturally generated structures throughout the game, and some are a lot rarer than others. Most biomes have their own structures that can only generate in that biome, and other structures, such as villages, can spawn in basically any biome. Minecraft: rarest structures
The Woodland Mansions were added to Minecraft in version 1.11 and were first revealed at MineCon 2016. Woodland Mansions are inhabited by hostile creatures, including evokers and vindicators. These mansions are only found in dark forest biomes or their hill variants. Inside the mansion, players can find lots of loot throughout the many rooms. If players want to find one, they will have to walk for quite a while. Woodland Mansions are very rare due to dark forest biomes typically only generating tens of thousands of blocks away from spawn.
Strongholds are underground structures that hold the portal to reach the End. Eye of Enders will point players in the right direction to finding a stronghold. It is almost unheard of to find a stronghold while simply mining or exploring. These structures are considered so rare because only three strongholds will spawn in each Minecraft world, so it is incredibly hard to find them, even with help.
The insides of witch huts include an empty cauldron, a crafting table, and a flowerpot with a red mushroom. Witch huts, also known as swamp huts, have been in Minecraft since version 1.4.2, making them an ancient structure, having been in Minecraft for years. Witch huts typically can only be found in swamp biomes, but they can also spawn in the swamp hills variant biomes.
Fossils generate underground in swamp and desert biomes, including their variants. Each chunk has a 1 in 64th chance of a fossil spawning. Many seasoned Minecraft players do not even know that fossils can be found.