(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 present study 
examined airborne microbe levels inside and outside passenger .... Bacteria, 
fungi and biokarst in Lechuguilla Cave, Carlsbad Caverns National Park, New 
Mexico ...