Oceanside Spider House

In Majora's Mask,the Oceanside Spider House is a building found on the Great Bay Coast. It's full of Gold Skulltulas that have cast a curse upon this place. The Oceanside Spider House bears a greater resemblance to a house than its Southern Swamp counterpart, the Swamp Spider House, albeit a very abandoned house, full of storage boxes and cobwebs. In order to get to the inner part of the Spider House, the entrance must be blown up using bombs (and, to proceed further, the Hookshot is a must).

There is a great library within the house, although some number of books are missing from the shelves, allowing Link to climb them. The library and what appears to be a dining room are inhabited by several Stalchildren, who are exploring the house, attempting to uncover any supposed "secrets" inside ; whether they are referring to treasure, the house's lone Piece of Heart, or something else entirely is unknown, but the six of them together reveal the order in which four masks in the dining room should be shot in order to reveal the aforementioned Piece of Heart through their own respective dialogs.

Possibly the most intriguing mystery surrounding the Oceanside Spider House is the presence of pictures of Skull Kid within the house. It is never elaborated on as to why these pictures are here, nor even referenced by anyone within the house, even Tatl. The only purpose they serve is to be shot down to potentially reveal another Gold Skulltula.

Once the 30 Gold Skulltulas are slain and their spirits collected, a man will appear at the entrance who will thank Link for killing the spiders and ask if he can have the house. Assuming that it's still Day 1, Link will be rewarded with the Giant Wallet. On any other day, he will merely receive a Purple Rupee. The man wants to use the Oceanside Spider House as a shelter from the falling moon.

Trivia

 * The man seeking for the shelter resembles one of the children from the Skulltula Family.