Dust darters were tiny insect Rahi which dwelt in the realm of Karzahni and fed on metallic protodermis. They were relatively harmless individually, but over time a swarm could do severe damage to anything metallic or mechanical. They were considered pests.
Dust darters were barely big enough to be seen by the naked eye. They lived in and around the dust falls of Karzahni. As a swarm they looked like nothing more than a cloud of dust, which helped to camouflage them from predators. Although they seemed harmless, they could do damage over a long period of time, since they fed off of metallic protodermis. Over time, they could weaken the armor of a Manas or worsen the damage to a Matoran's mechanical parts. Inside Karzahni, one could hear the almost rhythmic sound of metal striking rock as Matoran swatted dust darters.