Keratin

The Keratin were a race of advanced slug-like beings, capable of using gold to conduct and amplify their psychic powers. In 2008 they contacted Dr Francis Augur at the Auriga Clinic, who agreed to help them conduct their experiments on gold in salt water. They told him they needed to take control of people to overcome the language barrier, but were really enslaving them since, being slugs, salt was deadly to them. Their plan was to develop a bacteria which would boil away Earth's oceans in a day, destroying all life on the planet but exposing millions of tons of gold to aid them in their conquest of the universe. The plan was defeated by Sarah Jane Smith, and the Keratin representative on Earth was killed when Dr Auger injected it with salt water. (SJAA: The Glittering Storm)