All of the creatures of Fraggle Rock are connected through radishes. The Doozers make Doozer sticks, their building material, out of ground-up radish dust. The Fraggles' two main food sources are radishes and Doozer sticks. The Gorgs need radishes to make their youth and beauty cream...and if they don't use the cream, they vanish! This environmental interconnection is one of the main overarching themes of the series.
This is the first episode in which the Doozers are treated as separate characters; in early episodes, they merely act like little robots.