Calcium

Calcium was a chemical element. Unlike most other life-forms, the bodies of Raxacoricofallapatorians were calcium-based. (TV: World War Three) The Abzorbalovians of Clom, the twin planet of Raxacoricofallapatorius, had the same "greenish", living calcium skin. (PROSE: The Time Traveller's Almanac)

In 1903, after receiving a wealth of information from the future, Grigori Rasputin foresaw, among other things, creatures made of calcium. (AUDIO: The Wanderer)