Nebula Dragons are nocturnal creatures. With the best eyesight to be found, they are often seen staring into space. Each dragon tends to observe a particular nebula and will eventually change their colors and patterns to match it. As the nebula changes over time, the dragon changes with it. The more intricate the design of the nebula, the better chance an individual has of attracting a mate. It is said that the markings on no two Nebula Dragons will be exactly the same.

Dragons are highly-intelligent reptilian creatures that—from a human perspective, at least—appear to live forever. Many different varieties of dragon exist, each with their own unique qualities, habitats, and behavior. Adolescence in dragons is usually marked by the growth of a hatchling’s wings, although not all breeds of dragons grow wings and some breeds have other traits that indicate the beginning of maturation. In Galsreim, dragons and humans coexist peacefully.

Galacryo loves space--perhaps more so than Space himself. When Galacryo was but a hatchling, it was Space who found the little one on top of a mysterious hill, taking him to the Team Cydragon headquarters in the Separator Territories and giving him to Autumn.

Raising Galacryo was no easy task. He was roudy, loudmouthed, and always wanted to talk about space. Only Space could keep the Nebula under control, mainly because the two could yammer on and on, speaking in random sentences and centering their thoughts on space. He grew close to the Core, and started calling himself the Galaxy Core at one point.

Galacryo vanished one night, after exploring around the mysterious hill where he had been found. Some said that he was taken back to where he came from, while others say he joined the Replicators. Space has a different idea, one that he dares not speak of except to Wheatley, Rick, Curiosity, and Autumn: Galacryo could have been taken into the Aperture Canyons, where GLaDOS lives.