|MadSci Network: General Biology|
Dear Christopher, I am guessing that you mean an organism constructed entirely or mostly out of the familiar malleable metals, such iron, aluminum, copper. I don't think such a creature could originate and evolve on its own. Earth-based organisms heavily rely on polymers (long-chain molecules). For example, DNA and proteins (including enzymes, our skins, muscles, the collagen in our bones, etc.) are all polymers. One reason why metals don't appear to be suitable as the main building blocks of life is that they don't readily form polymers. Universal abundance may also be a problem. Hydrogen, oxygen, nitrogen, carbon and sulfur are five of the 10 most abundant elements in the universe. It may not be a coincidence that they are also among the 10 most abundant elements that make up the organisms. In contrast, there is only one malleable metal, iron, in the list of 10 most abundant elements in the universe. Probably one can come up with other reasons as to why an entirely metallic organism is not feasible. However, it may be possible for a carbon-based organism (similar to those on earth) to evolve a metallic outer layer as a protective shield. This could happen if the organism lived in an environment where a suitable metal was abundant and if such a shield would increase the chances of survival of the organism. If the organism already used that metal in some of its metabolic reactions, from those metabolic reactions additional steps could theoretically evolve to deposit the metal in the form of a shell. The overall process would be similar to the way snails build their shells from calcium carbonate. Was this an idea for a Halloween costume?
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