Field of Science


In the science-fiction/monster movie "Monolith-Monster" (1957) fragments of a meteorite are discovered in the desert of California. The strange mineral from outer space starts to grow to gigantic crystals when it comes into contact to water and a heavy rainfall is occurring in the mountains where the fragments are scattered around (the movie is also worth to watch for the geo-babble as noted by Jessica Ball in her Geological Frigthfest review on Magma cum Laude; and you can see here for yourself).  The idea of growing minerals was later adapted in the computer game "Command & Conquer: Tiberium", where an extraterrestrial meteorite brings the unknown mineral Tiberium to earth, that grows by extracting nutrients from all other life-forms.
Every single fragment of these crystals can grow, similar to real crystals; however they are not considered life-forms as they lack the ability to actively self-replicate or even evolve.

On earth the dominant life-forms are based on the element carbon (C) - excluding the case of the presumed arsenic bacteria -  but already early science-fiction writers speculated on alternative forms of life, based on other elements like silicon, nitrogen, phosphorus, boron and even metals like titanium, aluminium, magnesium and iron.

In 1891 the German astrophysicist Julius Schreiner was one of the first to propose silicon (Si) life-forms, the  idea was taken seriously by British chemist Emerson Reynolds who speculated about the habitats that such a creature could be inhabit.
Later H.G. Wells wrote

"One is startled towards fantastic imaginings by such a suggestion: visions of silicon-aluminium organisms - why not silicon-aluminium men at once? - wandering through an atmosphere of gaseous sulphur, let us say, by the shores of a sea of liquid iron some thousand degrees or so above the temperature of a blast furnace."

Silicon was chosen because its similarities to carbon - it is common in the universe and it can form log and stable polymers, it also reacts with hydrogen (forming the instable gas silane) and oxygen (forming stable silicones) to form stable molecules. Oxidation is used by terrestrial life forms to gain energy and the waste product is the gas carbon dioxide. A silicon creature would however produce a solid mineral composed of silicon dioxide. According to some authors the respiratory system of a silicon life-form therefore must produces sand or even bricks.
The idea became popular in the short story "A Martian Odyssey", published in 1934 by Stanley Weisbaum (1902-1935):

"Those bricks were its waste matter... We're carbon, and our waste is carbon dioxide, and this thing is silicon, and its waste is silicon dioxide-silica. But silica is a solid, hence the bricks. And it builds itself in, and when it is covered, it moves over to a fresh place to start over."

Aliens as silicon life-forms became very popular in TV-productions and movies also after the Monolith-Monster. The "Island of Terror" (1966) is inhabited by artificial "silicates" life-form that feed on calcium of human bones.

As a matter of fact the very incarnation of the extraterrestrial xenomorph -H.R. Giger´s "Alien" - possesses a shell of Si-compounds to protect it from environmental factors. This resistant shell is also very useful to contain the acid blood of the creature.
In the TV series "Star Trek" the crew discovers a silicon-based life-form during mining activities on the planet Janus VI (episode "Devil in the Dark"), however this creature is less hostile than other xenomorphs:

Spock: "Life as we know it, is universally based on some combination of carbon compounds. But what if life exists based on other element. For instance silicon."

In "Star Trek: The Next Generation" some episodes feature living crystals or the dangerous "Crystalline Entity".
In the X-file episode "Firewalker" a mushroom like parasitic life-form (however terrestrial in origin and the result of a parallel evolution process) produces as waste simple sand (that fills the lungs of its host). The parasite is discovered as spores coming from inside an active volcano start spreading. It is interesting to note that geneticist Haldane, J. B. S. proposed that silicon life-forms could survive inside a planet feeding on partially molten rocks.

Despite these promising visions, the structure of silicates is limited mostly on long chains or sheets (minerals). Silicon doesn't form complex molecules, like enzymes in carbon based life forms, and it would be difficult to achieve a metabolism with such a simple chemistry.


REYNOLDS, J.E. (1893): Address to the British Association for the Advancement of Science. Nature 48(477)
WELLS, H.G. (1894): Another Basis for Life. Saturday Review: 676


  1. I was going to add the "Devil in the Dark" episode if you hadn't recalled it. Good job!

  2. We had a competition during a late-semester Friday seminar to see who could spot the most geological errors in Monolith Monsters. I won with ~20-25 items, and though it was a few years ago I remember some highlights like "left microscope uncovered after use", "identified specific phase of amorphous silica at a glance", and I think "the geologist never drinks a beer."

  3. "the geologist never drinks a beer." - WOW - that´s unrealistic science-fiction....


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