(Kelly of the Clue Crew reports from inside Carlsbad Caverns Nat'l Park, New Mexico.)  Calcite formations called soda straws are precursors to these larger formations that grow from cave ceilings
The cavewide bacterial and fungal distribution, the large volumes of 
corrosion... [DOC] [TLE] microorganisms fungi bacteria: Topics by Science.gov [PAR] The clear zone diameters of these fungal isolates displayed significantly ..... 
Fungi and bacteria involved in desert varnish formation ...