How does Carl serve as a symbol in the novel, Absolutely Remarkable Thing?

From the start, April and Andy decide that Carl will represent “power and the future and the “other”” (70). The Carls do not need to move to scare people as their large, metallic appearance and the fact that they came from outer space is enough to create fear. Green uses Carl to symbolize the way in which humans react to things or even other people that they do not comprehend - with fear.