A religious sect (still in existence) discovered at the Concent of Saunt Byadin's at the 3rd Centenarian Apert. Listed by The Dictionary, 4th Edition, as one of the mishaps that lead to the creation of the Inquisition and the institution of the Heirarchs in their present form. Given as an example in the definition of "to go Hundred."
Matarrhites cover their entire bodies, excepting their eyes, with their bolt. They are also known to eat an unusual diet, but their true ways are largely unknown to others in the non-religious mathic world.
NB: Plot Spoiler
Shortly after Orolo sent a signal to the Daban Urnud, a commando team from the ship seized the Matarrhite math. The obscurity of their order and their dress allows the ship to send out spies posing as Matarrhites.