Matoran of LIGHT live here, as do the Brotherhood's greatest threat; Multiple future toa.
The Koro was massive, residing in a glowing cavern of lightstone spanning 300 kio. Stories have even said that the locals managed to convince a few of the shadow-eaters from another dimension to patrol the Koro and it's surrounding wahi cave for any Brotherhood attempts. Even the residents have taken up mastery of their elemental capabilities, using camouflage and protosteel cutting lasers by reflex.