Unnatural History Museum

The Unnatural History Museum is the ninth floor of The Last Resort in Luigi's Mansion 3. It is accessible after retrieving this floor's elevator button first from Paranormal Productions director Morty, then from Polterkitty. It is a museum filled with paleontology exhibits, including eggs, fossils, and skeletons of dinosaurs and pterosaurs. Its name is a pun on "."

This floor only has two rooms: a rectangle-shaped hall that surrounds the elevator, and the main exhibit area, which features a T-Rex skeleton, a Stegosaurus skeleton, and Raptor skeletons. As Luigi approaches the T-Rex skeleton, its pose changes every time the lightning strikes. There is a Toad painting next to the T-Rex skeleton, but when Luigi tries to free the Toad, the skeleton eats the painting and attacks Luigi. At first, the skeleton is attached to a pole. But after Luigi hits its chest with two eggs, it breaks free. Luigi then has to shatter the skeleton by shooting four bones at its chest. After doing so, it is revealed that a caveman ghost named Ug was controlling the skeleton. Ug grabs one of the bones and uses it as a club, attempting to hit Luigi with it. After capturing Ug, Luigi frees the blue Toad, who has the elevator button that leads to the second basement floor, the Boilerworks.

Rooms

 * Elevator Hall
 * Exhibit Hall

Gem locations
All six gems are found in the Elevator Hall.