Whomp's Fortress Interior

Whomp's Fortress Interior is an anomalous level found in some personalized copies of Super Mario 64. As the name suggests, the level takes place inside of Whomp's Fortress. The level is generally said to be a smaller stage similarly to Cold, Cold Crevasse, likely due to the fact that it takes place inside of another level. This is one of the most common anomalous levels, meaning there are several inconsistencies in reports.

Description
Whomp's Fortress Interior is described as a cavern-like area made out of bricks with several bottomless pits and boxes, as well as enemies such as Whomps, Thwomps, Goombas and Bob-ombs. A notable aspect of Whomp's Fortress Interior is that it reportedly has Whomps that can be interacted with that tend to talk about the construction of the fortress, King Whomp, and other aspects of the level.

The level is reportedly fairly linear, usually consisting of several connected hallways with moving platforms and "puzzles" to progress, reportedly using construction tools from when the fortress was being built according to some friendly Whomps. Notably, several jail cells can reportedly be seen throughout the level, either being empty, containing random enemies, Toads, or collectibles, usually either coins or Power Stars.

Missions
The most common star reported in Whomp's Fortress Interior is simply obtained by progressing to the end of the level, though some other stars commonly reported are obtained by unlocking a jail cell with a Power Star inside, as well as finding 8 red coins. Some other stars have been reportedly accessed by obtaining 5 secrets, breaking through a wall with a Power Star behind it similarly to the Whomp's Fortress 1-Up, and fighting a King Whomp rematch, similar to the anomalous rematch with King Whomp that has been reported in Tick Tock Clock.