ORGANO-MINERAL STRUCTURES, BIOMINERALS, AND EXCEPTIONAL FOSSIL PRESERVATION—A MICROCOSM OF THE INFLUENCE OF IRON OXIDIZING MICROBES ON THE FOSSIL RECORD
A single specimen of a filamentous organo-mineral structure was found within the mineral cavity of a three dimensionally preserved tubicolous fossil from the Deep Spring Formation. Similar to the minerals forming the cavity, abundant iron is found throughout the filament. The presence of iron without clear mineral growth suggests an intimate association between organic matter and mineral within the filament. However, crystal growth in both cubic and fibrous morphologies are also found growing within a substance reminiscent of Extracellular Polysaccharide. Modern iron-oxidizing bacteria are known to produce similar intricate organo-mineral structures in both marine and freshwater environments, however, like the preserving environment of the encasing fossil, this always occurs within microaerophilic conditions. The filament found within the Deep Spring tubicolous fossil superficially resembles such structures and likely contains organic matter. Determining the origin of this filament (whether recent or ancient) is paramount in understanding the long-term survival of such structures as well as assessing their usefulness as bioindicators in the search for life on Mars and the deep-time history of life on Earth.