Ba'ul pylon
Devices described as pylons were used by the Ba'ul to monitor the Kelpiens. There was a pylon placed in every Kelpien village on Kaminar, 4,056 in total as of 2257, which led the Kelpiens to call the Ba'ul the "Watchful Eye". All the pylons were connected to an incredibly vast network, and were controlled from a massive underwater Ba'ul stronghold.

In addition to surveillance, the pylons summoned Kelpiens undergoing vahar'ai to be harvested, during which Kelpien priests would guide the sacrificial victims to sit around the base of the pylon for transport to a Ba'ul ship. The pylons were also weaponized, giving the Ba'ul the option to destroy the local Kelpien village if they deemed it necessary.

In 2257, a pylon relayed the presence of Commanders Saru and Michael Burnham on Kaminar to the Ba'ul High Council. After Saru, with help from the  crew, broadcasted a signal through the pylon network that triggered vahar'ai within the entire Kelpien population, the Ba'ul stronghold surfaced and activated all the pylons in an effort to wipe out the Kelpiens. This was stopped by the Red Angel, who generated an immense electromagnetic pulse that deactivated and destroyed every pylon. (; )
Communications technology
Sensor technology
Structures