The Tandoka Scale as used by the migrant Bees escaping the Medusa Cascade.
The Tandoka Scale was a scale used by migrant Bees from Melissa Majoria as carrier signals.
When the Earth was stolen, the Bees used the Tandoka Scale to travel home. The Tenth Doctor traced the signals and took the TARDIS to the Medusa Cascade. (DW: The Stolen Earth)