Trollers were huge, horned, worm-like beasts that lived beneath the Po-Metru sands. Like all Rahi, they were created by Makuta Viruses and liquid Protodermis.
A Troller's mouth was said to be large enough to swallow an entire block of a Metru. They were one of the most dangerous Rahi in Po-Metru.
One of them was encountered by Toa Metru Onewa, Nuju, Whenua and Turaga Lhikan when they broke out of their cell inside the Dark Hunter Prison.
Onewa then used his Kanohi Komau to control the Rahi's mind and have it take them safely through the Metru inside of its mouth.
Some time later, a Rahi called Krahka briefly shapeshifted into a Troller during her battle with Roodaka.