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For questions related to the biology of extra-terrestrial organisms. This tag implies the use of the science-fiction tag. Use the science-based or hard-science tags to impose greater scientific restrictions (see warning in tag wiki). The goal of this tag is to answer the question using known science.

Questions tagged with the xenobiology tag should ask about biochemistry, biology, physiology, or chemistry as it relates to alien life. This tag cannot be used with the tag.

Questions relating to xenobiology do not ask about the aesthetics of a creature or how it interacts with its environment, but ask about the rationale that gives the creature life. Questions about biology-related aesthetics or environmental interaction should use the tag.

Warning: Despite defaulting to , this tag seeks already to use what science humanity knows to answer the question. However, humanity has not found life anywhere other than on Earth and studies into the possibility of life not natural to Earth are in their infancy. Users should understand that it's rarely possible to fully rationalize proposed alien life.

Therefore, users seeking to make their fantastic alien beings "as realistic as possible" are warned to avoid using the and tags unless they have performed the necessary research to ask a or question. If you choose to use either of those tags anyway, you are required to explain your research and explain why it failed to answer your question. Questions tagged with or that fail to provide those two explanations will have the tags removed.