- "I beg of you...In here...Find them all...The gold ones...The cursed spiders...Defeat them...Quickly!"
- — Swamp Spider House Resident
The Swamp Spider House, also known as the Fearful Spider House, is a location from The Legend of Zelda: Majora's Mask. This house, filled with Gold Skulltulas, is found in the Southern Swamp. The man found there was given the Mask of Truth by an unknown person, who told him that he would become rich should he follow a set of instructions inside the mask. However, when he put it on, he was instead cursed by the Gold Skulltulas, turning into a Skulltula-like creature himself. The only way to lift the curse is for the thirty Gold Skulltulas in the house to be killed and their Gold Skulltula Spirits harvested as proof of their defeat.
The entrance to the house itself is blocked by a web that must be burned in order to gain entry. Magic Beans are quite useful, as several Gold Skulltula Spirits are difficult to reach without the flying platforms that the beans provide; however, this problem can be circumvented by the extra jumping distance provided by rolling into a jump or using the Bunny Hood, or by acquiring the spirits from a distance with Zora Link's boomerangs or the Hookshot. Gold Skulltulas are hidden all throughout the house, frequently obscured from view by pillars, pots, or other obstacles. Link must use a variety of skills to find all thirty Gold Skulltulas.
Once all thirty Gold Skulltulas are defeated and their spirits collected, the curse upon the man is lifted, and he expresses his thanks by giving Link the Mask of Truth, which he is hasty to get rid of after having been cursed while attempting to use it.
The Mask of Truth never turns its wearer into a monster by itself.
The man wears the mask because of greed. This is shown by both the story as to how he turned into a monster and, when Link picks up the dog in the same room as the man while wearing the Mask of Truth, he is told that his master wore the mask due to his greed. Clearly, when the man put the mask on, he was performing an act of greed.
In Hyrule, specifically Ocarina of Time, Link sees an entire family that is cursed due to its greed. The physical manifestation of the curse involved spiders dispersed throughout Hyrule and the family being turned into spiders. This curse being born from greed is shown to exist.
The location itself was known for spiders in the first place. Outside, Link can read a sign stating, "Fearful Spider House," clearly referring to the cave behind it. Given the fact that the dog is in good health and not dead due to starving, the cave was obviously referred to as the Fearful Spider House before the man went there. This place is tied to the curse, and it was not simply the place chosen for the Gold Skulltulas to roam free due to its close proximity to where the man put on the mask. Instead, it was simply "activated", for lack of a better term. The switch is performing an act of greed in or near it.