The crystal climber was a Rahi breed originally from Ko-Metru. They lived among the knowledge towers feeding on ice bats. They were considered pests because of their habit of infesting tower chambers and refusing to leave. They later migrated to the frosty wastes of Mount Ihu.
Crystal climbers could be seen high atop the cold crystal towers of Ko-Metru, scurrying from one icy rooftop to the next. The crystal climber had sharp claws for holding tight onto cold and slippery surfaces, as well as a long, thin tail for balance. They had excellent night vision. Their glowing red eyes were a common sight in the evening darkness in Ko-Metru. The crystal climber's preferred prey were the ice bats which nested high in the knowledge towers. Although the ice bats were regarded as pests, crystal climbers were also unwelcome because of their tendency to stay rooted in a particular area which they felt to be good for hunting, becoming almost impossible to remove. Tower chambers had needed to be closed temporarily while Vahki tried to remove them. Crystal climbers formed small, tight-knit groups and reacted violently to intrusions by other members of their species. Ko-Matoran theorized that this was because too many crystal climbers in one spot could cause portions of knowledge towers to collapse and that they had learned not to congregate in large numbers.
With so few Vahki left after the Great Cataclysm, crystal climbers settled permanently in the knowledge towers.
Iruini remarked that the trick to catching crystal climbers was reaching them at the very highest points in knowledge towers, which made for very dangerous climbing. Additionally, the Rahaga needed to make sure the crystal climber did not fall off the tower once snagged with a spinner.
Ice bats were the preferred prey of crystal climbers.