Metal-based Life
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Basic Information

Some metals can form complex molecules that might just be able to support alien biochemistry. Beneath carbon and silicon, there is germanium, a metalloid which can form polymers known as polygermanes and is used as a semiconductor. There are also polymers known as polystannanes which are made from tin, and aluminum-oxygen-silicon polymers, or geopolymers, used as cement. The last natural element below carbon, lead, would make a poor backbone with its weak bonds, but might be incorporated in a secondary manner. A possible component might be polyoxometalates, which have been observed to form porous metal oxide bubbles that might act in the same way as biological cells.

A metallic biochemistry might be suitable for higher temperatures, and different varieties may be able to work in an extremely wide range of environments. A metallic species could have a metabolism based on simple metal compounds, as used by some bacteria species, or use non-metals such as oxygen or hydrogen. They might even be robotic in origin and rely on mechanical, not biochemical, workings to sustain themselves. The metals are not quite as suitable as carbon for biochemistry, but multiple elements can be used for different functions and there are plenty of options to choose from. They might expand these options by using metal-organic complexes, or incorporating silicon polymers similar to Silicon-Based Life.

How might metal-based life look? It won't necessarily have a shiny and metallic skin, though it might. It might use tough resins and rubbers based on metals mixed with oxygen, carbon, or silicon to form their bodies, some of which may be quite soft, and have insides moist with inorganic oils. It may be decorated with extravagant heavy metal paints, such as crimson lead oxide. The decomposition of metal-based biomatter would be just as messy as its organic counterpart, with soluble oxides and heavy metals leaching out, flammable metal hydride gases such as germane and stannane released, and even an elemental metal sheen forming as the simple metal compounds break down. Their native vistas would seem exotic, with even the soils made from metallic detritus, yet in many ways quite familiar.


Game and Story Use

  • Anything from a metal oxide algal sphere that lives in watery oceans, to mostly tin-based Sulfur-Breathing Life that swims brimstone lakes, is a possibility.
  • They might be exploited as a way to mine metals from a world, amongst other things. But life can adapt and grow out of control…
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