Kestora

"We are the Kestora. We are the ones who keep this place operating. But it has not been operating, not for a very long time. And it is his fault."

- A Kestora, The Powers That Be.

The Kestora were a race of sapient purple and black beings which resided in the City of Silver Pocket Dimension, as well as the Red Star.

Main Universe
At some point, in the prime universe, a transformed Matoran named Gaardus arrived on the Red Star. Some Kestora then met him. Gaardus eventually left the star.

After Tren Krom's death, Gaardus brought Kopaka and Pohatu back to the Red Star, where they were greeted by three Kestora. Recognizing Gaardus, the beings produced three weapons. Gaardus then teleported away. The Kestora informed the two Toa that the Red Star was a type of transport hub and, after learning Mata Nui was disabled, argued over what to do with them, until they were flash-frozen by Kopaka.

City of Silver
When Takanuva arrived in the pocket dimension, he received information from the Spectral Mask that a village was in trouble. Without hearing the complete message of the Mask, Takanuva immediately rushed off, where he saw crowds of the Kestora fighting against a large creature. Deciding that the creature was the source of the commotion and what he had to combat, Takanuva fended off the creature, believing to have saved the entities.

However, they laughed at Takanuva instead, and locked him out of the village. It was later that Takanuva learned the entities were actually trying to chase the last of the creatures out of the village, to whom the village actually belonged. Realizing his mistake, Takanuva consulted with the creature and enacted a plan to lure the Kestora out of the village. He stood outside of the village and created many large fireworks, and the entities flooded out of their village to watch. While they admired the fireworks, the creature burrowed back into the village and locked the Kestora out.

Personality
Kestora were not as advanced as Matoran, and were limited by the parameters of their AI's original genetic programming. Lacking individuality as well as a concept of morality, the Kestora were focused solely on their original purpose of returning beings revived in the Red Star to the Matoran Universe, and were determined to achieve this at all costs, even at the cost of the lives of others. They had no sense of compassion or empathy, and were not above dissecting their revived charges if it could enable them to do their jobs.