> If a shadow biosphere were ever found... ...it would automatically become part of the biosphere. Note that an entire kingdom of life, the Archaea, was only i

> If a shadow biosphere were ever found... ...it would automatically become part of the biosphere. Note that an entire kingdom of life, the Archaea, was only identified in 1977[1]. That was a "shadow biosphere" if you like: an entire separate version of life, unidentified as such until we could sequence RNA. But at least some species of Archaea were known long before, just inadequately classified. N.B. "Desert Varnish" is not at all the mystery the article suggests[2] and the idea that it represents some kind of biology seems extremely improbable: "Microscopic and microchemical observations, however, show that a major part of varnish is clay, which could only arrive by wind.[5] Clay, then, acts as a substrate to catch additional substances that chemically react together when the rock reaches high temperatures in the desert sun. Wetting by dew is also important in the process.[3]" [1] https://en.wikipedia.org/wiki/Archaea https://en.wikipedia.org/wiki/Archaea [2]https://en.wikipedia.org/wiki/Archaea https://en.wikipedia.org/wiki/Archaea