Source: MTV Geek
The Ro-Bear Berbils are partly furred robot-bears from the planet Ro-Bear. Because their homeworld is so tiny, they must form other colonies on distant worlds to survive. Small and harmless-looking, the Berbils are steadfast, hardy workers and skilled farmers, cooks and craftsmen. It was thanks to them that Tygra was able to build Cat’s Lair — and later the Tower of Omens — so quickly. Apparently, the Ro-Bear Berbils are Cybernetic organisms, as they are able to eat and digest organic food. Ro-Bear-Bill and Ro-Bear-Belle are the leaders of the nearby Ro-Bear Berbil village, these robot-bears are the first to befriend the ThunderCats and often supply information about local places, people and phenomena on Third Earth. Through their fields and forests of Fruit Trees, they are also able to provide the Thundereans with new foodstuffs.
It was revealed that two Ro-Bear Berbils had saved Lynx-O, Bengali, and Pumyra from the destruction of Thundera. Their ship was damaged upon evading the explosion of Thundera and landed on an island on Third Earth since it didn't have any more power to get back to the Berbil Village. The two Berbils alongside the other three ThunderCats ends up landing on an uninhabited island where they lived until they were caught by Hammerhand and his pirates. The two Berbils were later rescued by the ThunderCats and assumed to have been reunited with the other Berbils.