The Kallidahin were a sentient species of humanoids notable for their absence of facial features. Their origins trace back to Kallidah, yet they also established a presence within the asteroid field surrounding Polis Massa. Due to their prolonged habitation on this planetoid, they became recognized as Polis Massans. These particular Kallidahins, functioning as archaeologists and exobiologists, adopted certain cloning methods from the Kaminoans in an effort to regenerate life from tissue samples obtained during archaeological excavations. Their excavation of Polis Massa was motivated by the desire to unearth remains of the extinct Eellayin civilization, who were ancestral to the Kallidahin. Typically, Kallidahin were characterized by their silence, relying solely on telepathy for communication. Despite lacking facial mouths or noses, they retained the capacity to speak and breathe. Their physical traits included a small, wiry build and hands with four fingers. Among the Kallidahin was Utani Xane, a curator who met his death at the hands of Darth Vader during the theft of the Triple-Zero protocol personality matrix. The Kallidahins stationed on Polis Massa made an attempt to save Padmé Amidala when she died during the delivery of Luke and Leia.
The first appearance of the Kallidahin was in the 2005 film Star Wars: Episode III Revenge of the Sith. According to a statement made by Leland Chee on Twitter, some Kallidahin, though it is unusual, possess vocal cords.