Planet of origin: Gunn, a desertic planet saturated with sulfuric gases orbiting a red giant star in the Mikly Way galaxy.
Buu are a balloon-like floater species with three short pair of arms, each with two digits. They have one mouth and a pair of eyes on the front of their body. They are peaceful social creatures and live in pack but do not appear to have develop much technology.
They have been studied by the Kroons.
Source: Spirou Magazine issue 1973, 1975, pp91-92. in the short story "L'ancètre" (The Ancestor), by Michel Pierret and Francis Carin. Note: This story is based on the Smurfs character created by Peyo. Although it figures in the same media as the Smurfs, its canonicity in the official Smurf franchise remains debattable. Given the rarity of this story, which has to our knowledge, never been republished, it nevertheless remains, by the incredible amount of visual and text informations it delivers in the two pages it lasts, a very cool piece of pop culture. Thanks to the authors!