A seemingly empty planet whose natural crystal transmitter and peaceful native lifeforms became pivotal in Starfleet's effort to detect cloaked Klingon ships.
Pahvo is a seemingly uninhabited planet visited in Si Vis Pacem, Para Bellum. A naturally occurring crystalline transmitter broadcasts the planet's vibrational frequency into space, and Michael Burnham, Ash Tyler and Saru are sent to adapt it into a sonar for finding cloaked Klingon vessels. The planet proves to be home to indigenous lifeforms that show Saru their sense of peace, and he tries to keep his companions there forever.
The Pahvans alter the signal so it also reaches the Klingons, hoping to end the war. In Into the Forest I Go, Gabriel Lorca disobeys orders and stays to defend the planet when Kol's ship arrives.