Tythonian communicator

The Tythonian Communicator is a device that Erato used to communicate with.

The Tythonian Communicator is a flat, heptagonal device with five panels and a knob in the middle. If someone is touching the knob, the Tythonian can use their vocal chords to communicate. While the person is touching the knob, Erato has complete control over what they say. It can apparently work from a distance and on robots, since K-9 was used to communicate while Erato was outside the TARDIS. (DW: The Creature from the Pit)

As well, the communicator was used to control several bandits, which made them move the Communicator closer to Erato.