 The series features "sky flowers" as a main setting material. They first appeared in the pilot and have since become a common feature throughout the series. When series background designer Kenny Pittenger was asked what they were, he answered, "They function as clouds in a way, but since the show takes place underwater, they aren 't really clouds". Since the series was influenced by tiki, the background painters have to use a lot of pattern. Pittenger said that the sky flowers were meant to "evoke the look of a flower-print Hawaiian shirt".
