Mask of Scents

The Mask of Scents is a pig face-shaped mask from Majora's Mask.

Location
The Mask of Scents is given to Link by the Deku Butler, but only if he beats him in his race. After clearing the Woodfall Temple and bringing the Deku Princess back to Deku Palace, Link needs to talk to the Deku Butler. He's waiting to meet the young hero in the Deku Shrine outside of the palace. Once there, he will ask Link to race him, a race that is far easier to complete with the Bunny Hood equipped. If Link manages to keeps up, he will say how it reminds him of racing with his son, and gives him the Mask of Scents in return.

Uses
It imbues the wearer with the ability to sniff for the scent of and find Magic Mushrooms, two of which are given to Kotake to create Blue Potions. Because Blue Potions can be bought elsewhere (although for more Rupees), and given the obscurity of the mushroom's location, the use of the mask is relatively rare; however, Link can still receive a free Blue Potion in exchange for the Mushroom.

Link's voice changes when the mask is donned, and he snorts and grunts like a pig when he rolls or swings his sword. Mushrooms will appear as a cloud of purple mist and can be scooped into a bottle. The mask is owned by the Deku Butler, but was originally owned by his son.

Trivia

 * This mask is also an unconfirmed easter egg as it is one of the five masks that resembles a character from the Star Fox Series (in this case being Pigma).