A bleach nut is a laundry implement referenced to and used by Boober in the Second Season Fraggle Rock episode Boober Rock. It is not certain what its function is, but when struck it emits gas vapors which are the antidote for the Cave of Forgetfulness' own gases.

It is revealed in Episode 223: Boober's Quiet Day that bleach nuts come from the "Lilac Cavern" - an overnight trip for Boober.