Helmet

The Helmet is an item in the game Super Paper Mario. When Mario reached Outer Space, he could not breathe at all. To solve this problem, he set out on a quest to get something that would help him breathe in space. Mario then came across, Pook, who gave him his Goldfish Bowl. After dumping out Captain Gills into the sewers, Mario used it as his helmet in space.

A helmet also appears in Super Mario Sunshine. During certain missions in Noki Bay, Mario would borrow a helmet from the Noki Elder's Son. When used, it would prolong Mario's abilty to stay underwater. However, Mario still needed air whenever his life gauge was getting low, so he would replenish it by breathing air bubbles.

Trivia
Captain Olimar (from the Pikmin games) has a helmet similar to this one.