Nexus (Contact '57)

The Nexus is the hive-mind-like network used by the Sen'kaal to telepathically communicate. It is believed to work via neutrino pulses. Those Sen'kaal (and humans) capable of sensing and using the Nexus are known as Nexus-sensitives or biotics.

Role in the Sen'kaal Dominarchy
Within the Dominarchy, the Nexus serves as a sort of "internet" through which Sen'kaal can communicate, commanders can relay orders, and information can be transferred.