Lava World

Mount Fire Eyes was a unfinished world that was planned to be released in Banjo-Kazooie. Due to insufficient time to complete development of the world, Rare did not feature the level in the game along with Fungus Forest and two other mysterious levels. They instead reused the level as the lava side of Hailfire Peaks in Banjo-Tooie. Like Fungus Forest, there is a direct reference to this level in Banjo-Kazooie in Click Clock Wood, after stealing Gobi's water for a second time he will state that he is going to go to the 'Lava World'. Although in the second game it turns out he was heading for Hailfire Peaks, it is thought that in the original game he had meant he was heading to Mount Fire Eyes, which, with Click Clock Wood's late appearance in the game, it is presumed that Mount Fire Eyes would have appeared even later than that level.