The hooloovoo is a super-intelligent shade of the colour blue. One was seen as a prism for Zaphod Beeblebrox's address upon stealing the Heart of Gold. On certain special occasions, such as the aforementioned Beeblebrox address, they will be refracted into a free-standing prism. The hooloovoo demonstrate their dissatisfaction with the Universe by holding their breath until they turn a deep purple.