Question

Cyanobacteria came into existence ....... years ago.

• A. 2.9 billion
• B. 3.4 billion
• C. 1 million
• D. 44 thousands

Answer 1

The correct option is B 3.4 billion

Stromatolites are layered bio-chemical structures formed in shallow water by the trapping, binding and cementation of sediments by microorganisms, especially cyanobacteria. Stromatolites provide ancient records of life on earth by fossil remains, which might date from more than 3.5 billion years ago.