Priest Triangle

Priest Triangles were small sentient crystalline pyramids with the capacity to fly. They were assigned to maintain the Temple of Atropos and Mouri.

They believed that Time in its natural form was evil and were intimately convinced of the importance of the Mouri remaining in place; however, they either did not know who had assigned the Mouri or were bound not to reveal it. They had the capacity to do normal maintenance work but not in-depth repairs; after Swarm and Azure damaged the Temple, wounding two of the six Mouri, the Triangles waited anxiously for someone to come repair and latched onto Inston-Vee Vinder and Yasmin Khan as potential saviours after they were transported to the Temple by the Flux.

Shortly after they had shown Vinder and Yaz the damage, however, Swarm and Azure returned to the Temple with a Passenger form. Azure destroyed one of the Priest Triangles shortly after they arrived; the second one remained above the Mouri's platform until after Azure and Swarm had met Vinder and Yaz. However, after Azure realised, thinking aloud, that the Mouri had been quantum-locked against herself and Swarm "after last time", the second Triangle realised who the two of them were and began trying to drive them out. This prompted Azure to very casually destroy the second Triangle with a brush of her hand. (TV: War of the Sontarans)

Later, as the Thirteenth Doctor was about to leave in her TARDIS, a third Triangle flew towards her and asked her if she had managed to repair, to which she answered that she hoped she could before she went into the TARDIS. (TV: Once, Upon Time)

Behind the scenes

 * All Priest Triangles were voiced by Nigel Lambert.