Fountain of Youth

The Pool of Youth was a magical pool that appeared in The Super Mario Bros. Super Show! episode "Two Plumbers and a Baby / Lost Dog". This pool can make any person any age they want. There is a lever near the pool that can change the age the Pool of Youth will turn people into. During the episode, three elderly people tried to become eighteen again; however King Koopa pulled the lever and made the old men turn into babies instead. Princess Toadstool then fell in the Pool of Youth and was turned into a baby version of herself.

Mario and Luigi later returned the Pool of Youth to its original state, and transformed the princess to her normal age. Also, the brothers returned a lot of babies back to their old age. King Koopa was then thrown in the Pool of Youth and turned into a baby.