Species matcher

The Doctor uses a species identifier in order to determine the species of the monster Vincent van Gogh could see. The Doctor had a species identifier which he received from his godmother. Initially, the Doctor thought the identifier was pointless and a waste of space, until he needed to use it.

Abilities
The identifier was able to be strapped to the user and was able to identify any species of alien. It was even able to identify and show a Krafayis, a species which is usually invisible. When it finds a match, the identifier pings and gives the user information on the species, including name, planet of origin, and other information about it. Initially, when trying to identify the Krafayis using a drawing, the identifier had trouble, at first identifying it as a parrot and then as a polar bear.

It was also able to identify certain individuals of certain species, such as the Doctor. When it identified the Doctor, it displayed images of his first and second incarnations, and listed his planet as Gallifrey, though it did not mention the fact he was a Time Lord. (DW: Vincent and the Doctor)

Behind the scenes

 * The name "species identifier" is based on conjecture and was not actually used on screen.