Trilanic activator

A trilanic activator is a device created and used by the Zygons to control their Skarasens. (DW: Terror of the Zygons) When activated, it sends out a signal that says "eat me, eat me" and calls the Skarasen to wherever the control is. Like most Zygon technology, the trilanic activator is biological in design. It is hand-sized and has a texture like wet skin. It will activate and can be regenerated when in an area of high diastellic transmissions.

A group of Zygons used a trilanic activator in 1909 to control their two Skarasens. The Doctor later stole it and planned to use it to put the Skarasens to sleep. It was regained by the Zygons after the Doctor's capture. (NSA: Sting of the Zygons)

A trilanic activator activator was also used by Zygons in the 1970s. (DW: Terror of the Zygons)