Photosynthetic microbial mats forming large conical structures up to half a meter tall have been discovered by astrobiologists in Lake Untersee, Antarctica. This research is described in an article in the May 2011 issue of the journal Geobiology.
Lake Untersee is located at 71°20'S, 13°45'E in the Otto-von-Gruber-Gebirge (Gruber Mountains) of central Dronning Maud Land. The lake is 563 meters above sea level, with an area of 11.4 square kilometers and is the largest surface lake in East Antarctica.
During the expedition, three members of the field team, Dale Andersen (SETI Institute), Ian Hawes (University of Canterbury), and Chris McKay (NASA ARC) explored the lake beneath its 3 meter thick ice-cover and discovered the large conical structures that dominate the under-ice landscape.
To date, there have been no other reports of modern microbial mats forming such structures, which resemble a class of stromatolites termed large complex cones that were present on Earth approximately 3.4 billion years ago in the Pilbara (see Allwood et al. Nature, Vol 44, 2006).