Wrist device
From Tardis Wiki, the free Doctor Who reference
The Wrist device was a piece of technology of Silurian design.
They were worn by Silurian leaders and served as a way of controlling as well as charting the progress of a Myrka when it was set loose. Several buttons were present on the machine which was worn on the left arm and was capable of telling its user if the Myrka was successful or if it had been destroyed.
Icthar of the Triad wore one such device which he used to control the Myrka set to storm a Human base. (DW: Warriors of the Deep)
