Ice Age Exhibit
From the Super Mario Wiki
The Ice Age Exhibit is a room in Treacherous Mansion in Luigi's Mansion: Dark Moon. Located at the north west corner of the mansion, this room spans two floors and is themed after the Secret Mine (complete with the same music).
Inside, there's an igloo with an E-Gate to the east, some holes with fish near the south of the room, an ice cave with a trapped Toad and treasure chest to the west and a stage area with a Mammoth towards the back. There are also three extremely loud air conditioners that can be heard whenever Luigi is in this room.
There are three exits in this room. The south door leads to Grand West, the Mammoth can be interacted with to throw Luigi up to the Gargoyle Roof and there is an E-Gate that will take Luigi to the Front Entrance.
During Double Trouble, Luigi explores the Ice Age Exhibit to rescue one of the Toads trapped within a painting here. He has to make his way into the ice cave on the left to free him, after which some Sneakers attack.
During A Train to Catch, Luigi can bring a Bulb through the E-Gate from the Study to the Ice Age Exhibit to explore the upper floor for money and another gem. The Mammoth has also made its way to the ice cave and won't throw Luigi up to the Gargoyle Roof. It's tail can be pulled, but doing so will have no effect.
During Paranormal Chaos, the Ice Age Exhibit is filled with ghosts and must be cleared out during the mission. The mammoth is still hiding in the cave.