Silverfish spawners spawn Silverfish. There is a guaranteed silverfish spawner in the End Portal room of a stronghold. The only possible spawners a player can naturally find are a zombie spawner, spider spawner, skeleton spawner, cave spider spawner, Silverfish spawner, and Blaze spawner. Other spawners will not naturally spawn. It is impossible to pick up a spawner, even with silk touch. Dungeons have the chance of having a spider spawner, zombie spawner, or skeleton spawner. Abandonded Mineshafts have the chance to have a cave spider spawner. The End Portal room of a stronghold will always have a silverfish spawner. Blaze spawners will always spawn near the staircase balcony of a Nether Fortress. The only spawner a player can get in single player is a pig spawner, which will not naturally spawn. A spawner will spawn one, two, three, or four mobs at a time. If torches are placed on all sides of a mob spawner, the spawner will not spawn anything. Spawners give experience when mined. If a stack of spawners in mined, the player will get roughly 40 levels of experience.