Lava hawks were a Rahi bird of Voya Nui known for their immunity to molten lava. Matoran collected their scales to build crafts capable of surviving passage down the lava rivers.1
Notes
The lava hawk was a Rahi bird highly prized by the Matoran of Voya Nui, as it was completely invulnerable to the heat of molten lava. It hunted by diving straight into magma streams and feeding on insects that lived in the lava. Matoran collected the metallic scales it periodically shed from its wings to build craft capable of surviving passage down lava rivers.2
The lava hawk was not organic.3