Spawner generates exclusively in pre-built structures — dungeons (zombie, skeleton, spider), abandoned mineshafts (cave spider), Nether fortresses (blaze), and woodland mansions (vex). The texture is a black metal cage with a tiny rotating mob figure inside, indicating which entity it produces. The device cannot be crafted and cannot be obtained even with Silk Touch — mining always destroys it permanently.

When a player is within sixteen blocks, the device attempts to spawn its mob every ten to forty seconds, up to a cap of six entities in the immediate area. The spawn requires the same conditions the mob normally needs (light level, space) which is why most XP-grinder farms surround the spawner with darkness and water columns to channel mobs into a kill zone. The block also drops zero experience when destroyed, making preservation crucial — once gone, it cannot be replaced. Some servers use commands to change the mob inside, but in vanilla survival the entity is locked at world generation.