Moldorm is a recurring enemy in The Legend of Zelda series. It's appearance varries depending on the game but they generally are always some type of worms. They are either regular enemies or Bosses depending on the game. They are a very old enemy that debuted in The Legend of Zelda.
The Legend of Zelda
The Moldorms in The Legend of Zelda are supposed to look like gigantic realistic earthworms based on their artworks. In reality they appear as a string of orange balls due to the NES' limitations. They usually inhabits the sandy rooms of certain dungeons but can be found in regular dungeon rooms in some case. To defeat them, Link must destroy each of their segments individually. They don't respawn.
"The huge worm living in the labyrinths. It grows smaller as Link attacks. Not so strong."
The Legend of Zelda: A Link to the Past
Moldorm makes its debut as a boss in The Legend of Zelda: A Link to the Past. It is the boss of the third dungeon, the Tower of Hera, and will guard the Pendant of Wisdom needed to draw the Master Sword from its pedestal. It's body is once again segemented but this time the only vulnerable part is the tail. It is fought on a platform and it's main strategy is to run in random directions to throw Link off and eventually knock him down a few floor, which will reset the battle. After a few hits to the tail, Moldorm will be defeated and Link will be rewarded with a Heart Container and the Pendant of wisdom.
The Legend of Zelda: Link's Awakening
Moldorm is very similar to its A Link to the Past incarnation despite its distinct appearance in The Legend of Zelda: Link's Awakening. It appears both as the boss of Tail Cave and as a form of Nightmare during the final fight. Once again, it's weakness is its tail and it tries to push Link into holes.
The Legend of Zelda: Four Swords
Moldorm returns as a regular enemy in The Legend of Zelda: Four Swords. They are quite rare and act very similar to their past incarnations but can be attacked from every angles. They can drop highly valuable Rupees when defeated.
The Legend of Zelda: Four Swords Adventure
In The Legend of Zelda: Four Swords Adventures, the Moldorms are a regular enemies that are very similar to the A Link to the Past boss in appearance. They are only found in the Desert Temple and will move randomly in different directions. They will be defeated after a few hits.
The Legend of Zelda: The Minish Cap
In The Legend of Zelda: The Minish Cap, the Moldorms are small in size and mainly found in the Fortress of Winds. They are really quick and are usually in small spaces enclosed by dirt that must be dug away with the Mole Mitts. Their whole body is vulnerable to attacks.
The Minish Cap figurine
"Appears in various areas. These guys move quickly and randomly. Trap them in a corner and take them out quickly."
The Legend of Zelda: Twilight Princess
In The Legend of Zelda: Twilight Princess, they are sandworms with a giant gapping mouth and three gigantic teeth. They are found swimming in the sands of the Gerudo Desert where they will get close to Link and jump in the air to try to ram into him. They can be easily defeated by slashing at them with the sword while they are mid-air or he can just use the Clawshot to pull them out of the ground. Bigger ones can be found in the Arbiter's Grounds or if you defeat a group of smaller Moldorm in Gerudo desert.
The Legend of Zelda: Phantom Hourglass
In The Legend of Zelda: Phantom Hourglass, they appear more bug like. They are only found in the Temple of Courage and must be defeated by hitting their tails three times like they were dealt with in some of their past incarnations. They can alternatively be defeated with a single arrow shot in the tail.
The Legend of Zelda: A Link between Worlds
Moldorm returns as a boss in The Legend of Zelda: A Link Between Worlds. It is the boss of the Tower of Hera where he guard the Pendant of Power. A stronger purple Moldorm is also fought as one of the boss rematch in Lorule Castle. Both Moldorms are also fought in the Treacherous Tower, the yellow one is fought as the final enemy of beginner mode and the purple one is the last enemy of advanced mode.
They are similar to their A Link to the Past incarnation and are fought on a elevated platform. He can knock Link off of the platform but this time it will not reset the battle. It also get quicker after taking enough damage.
The Legend of Zelda: Tri Force Heroes
Moldorm is the boss of the Fire Temple in The Legend of Zelda: Tri Force Heroes. It's weak point is still its tail but it now is adapted to fight against three Link. Moldorm's eyes will emit green, red, or blue light, and it will pursue the Link whose tunic matches the current color of its eyes. If this Link is hit, Moldorm's tail will be briefly shielded and it will follow a differently colored Link. After being hit, its tail gets encased in a protective shell and it will start moving randomly in a mad state. After calming down, it will change the height of its tail, forcing the Links to form a Totem to reach it.