Mouse
From Tardis Wiki, the free Doctor Who reference
A mouse was a type of animal found on Earth and other parts of the universe.
On Gallifrey, a mouse was enlarged by the Rani during an experiment and ate the Lord President's pet cat. (DW: The Mark of the Rani)
In the year 4000, Froyn and Rhynmal intended to test their new long-range teleportation system by sending two lab mice to Mira. (DW: The Daleks' Master Plan)