Mercurial

Mercurials are a sapient, all-female species from the planet Mercury, where they live in caverns and come out into the sun to absorb energy. Their bodies are made out of a liquid silver-colored metallic substance, resembling mercury, thus giving two meanings to their species' name.

In addition to Mercury, Mercurials can be found inhabiting several other planets, and are often employed to perform jobs in places that would be uninhabitable for other species. They can withstand extremely high temperatures and reconstitute themselves after being blown up.

Appearances

 * Short Trips: The Solar System (2005)
 * Big Finish Eighth Doctor Adventures, Prisoner of the Sun (2011)