In The Legend of Zelda: A Link to the Past, Moldorm is a boss found at the top of The Tower of Hera. It is one of ten dungeon bosses found in the game, and while not the most difficult, has a unique type of challenge.
Moldorm is a segmented worm, that moves at unpredictable angles, and who can only be damaged by striking its tail. When he hits Link, he doesn't do much damage. But Link fights Moldorm on a platform suspended over a hole, and when hit by Moldorm, Link can fall down one (or two) floors, leading to Link having to reclimb the tower while the player's frustration mounts. (Leading to the fan nickname "Trolldorm")
Moldorm, and the arena that you fight it in, shows how much the technology of the Super Nintendo opened up gameplay. Rather than the room being a static set of tiles with a few changes in decoration, the room becomes a dynamic part of game play. It was one of many challenges that forced players to think through a problem, and not just mash buttons. And indeed, when the player patiently defeated Moldorm, they are rewarded with the pendant of wisdom.