Kurahk was a white Rahkshi who possessed a glacier-like sail on his back.
When Makuta Teridax learnt that Guurahk, Lerahk and Panrahk failed to capture Takua and claim the Kanohi Avokii in Ko-Koro, he immediately created three more Rahkshi; Turahk , Kurahk and Vorahk and sent them to find the herald and the mask.
Turahk, Kurahk and Vorahk eventually tracked Takua and Jaller in Onu-Koro. There, they ambushed Onu-Koro and attacked the Onu-Matoran. Kurahk managed to find Takua and was about to capture him when Tahu arrived and engaged Kurahk in the fight. During the battle, Kurahk enraged Tahu when the latter tried to protect Takua from his attack and caused him to attack Gali before eventually being frozen by Kopaka. Turahk, Kurahk and Vorahk continued to attack the Toa Nuva until Onua used his power to cave-in Onu-Koro, seemingly defeating the three Rahkshi.
However, Kurahk and the other two survived and continued to pursue Takua. Joined by Guurahk, Lerahk and Panrakh, Kurahk and the others resumed their pursuit of Takua and Jaller. They tracked the two Matoran to the temple of Kini-Nui, where they attempted to kill them. The Toa Nuva soon arrived and, uniting together, defeated the Rahkshi.
Kurahk's body was used to create the Ussanui along with the other Rahkshi.