Karda Nui, also known as the Universe Core or The World that Feeds the World, was a part of the Matoran Universe, and where the Av-Matoran first resided. Its name meant "Great Heart" in the Matoran Language. It contained the Stalactite Villages, the Swamp of Secrets, the Codrex, and the Shadow Leech Hive. Karda Nui was created by the Great Beings to regulate energy throughout Mata Nui's body and the Matoran Universe. This was directed by the Energy Storms. Karda Nui acted as Mata Nui's "heart."