From the Super Mario Wiki
Retrieved from "https://www.mariowiki.com/index.php?title=Phantom_Hand&oldid=2605294"
Phantom Hands are floating, disembodied gloves that point to secrets in New Super Mario Bros.. They only appear in World 7-, and their only purpose is to point out the location of an invisible block containing either a ? Switch or a power-up that moves back and forth to the player. They are not enemies, meaning that Mario or Luigi are not injured if they touch one, nor can they be defeated.