Linella avis Stromatolites

Geological Time: Neoproterozoic (800 Million Years Old)

Size (25.4 mm =1 inch): Stromatolite is 130 mm by 120 mm (maximum)

Fossil Site: Bitter Springs Formation, Alice Springs, Northern Territories, Australia

Fossil Code: AS12053

Price: Sold

Description: Stromatolites are remnants of the most ancient of colonial organisms. Stromatolites are fossils that are the result of the work of simple blue-green “algae” or Cyanophytes, which lived in chains or mats covered in a jellylike substance. By taking in carbon dioxide as a food source, the precipitate limy deposits on the jelly that builds up in layers. Thus these organisms build up stony supports for their colonies. These mound like structures can be anywhere from several centimeters to several meters in height. The production of oxygen is thought to have led to the “rusting of the seas” which brought about deposition of extensive iron deposits such as the Mesabi Range. Stromatolites have persisted to the modern day in such places as Shark Bay, Australia where they continue their billions of years old lifestyle. The digitate (fingerlike) dark structures seem here are individual colonies. It is thought that this region underwent seasonal submergence resulting in the structures you see here. By the Cambrian, photosynthetic bacteria responsible for the biogenic formation of stromatolite structures no longer had the earth to themselves. The oxygenated atmosphere had become toxic to some bacteria, and they had to compete with other organisms, some of which would have been predaceous to this most ancient of life forms.