• Stromatolites are laminated calcareous structures caused mainly by nonskeletal algae (generally cyanobacteria; blue-green and green algae) that date back to the early Precambrian. 
  • biosedimentary in origin, and resulting from the interaction of filamentous and coccoid algae, which are in the form of "algal-mats" and physical sedimentary processes.
  • perform a sediment stabilizing role by mechanically trapping and binding sediment particles on organic films.
  • The result is a well laminated stromatolite and oncolites or a poorly laminated structure and clotted fabrics.
Microbial mats cover the sediments of Shark Bay, Australia;
Courtesy of