Geology,
Speleology
Snotites are slimy, dripping cave formations that resemble
stalactites but look and feel like snot. They are actually enormous colonies of
bacteria (often
chemoautotroph extremophiles) that metabolize sulfur-containing minerals in groundwater known as
Thiobacilli.
The cave environment rich in snotites usually contains an abundance of
hydrogen sulfide gas, creating a smell of rotten eggs. The area in which the bacteria thrive is so acidic that
pH readings are often negative; drops of liquid that fall from the ends of snotites are acidic enough to dissolve clothing. The cause of this acidity is a combination of the formation of sulfuric acid through the reaction between
hydrogen sulfide gas and oxygen gas as well as the releasing of
sulfuric acid as a waste product of the bacteria.
The bacteria eventually form thick sheets of slime which gradually begin to drip from the ceiling. As the colonies grow, they release more and more
sulfuric acid, which gradually begins to eat away at the rock. These tiny microbes are often responsible for carving out vast underground labyrinths; geologists believe that some cave networks were first formed by bacteria thriving deep underground, feasting on
oil reserves and releasing hydrogen sulfide.
Research on snotites:
The existence of such microbes has led to speculation that similar subterranean lifeforms may exist on Mars.
DNA analysis of these bizzare microbes has aided in the discovery of new species of bacteria, protists, and nematodes.
Scientists are continually improving techniques used to grow cultures of such bacteria in lab so that the physiology and biochemistry of the organisms can be studied more easily.
See:
http://www.nasa.gov/vision/universe/solarsystem/cave_slime.html
http://www.i-pi.com/~diana/slime/villaluz/snottites/
http://www.nps.gov/wica/PBS/Special_Evening_Program.htm