How old are the oldest fossils on earth?

Question: How old are the oldest fossils on earth?
- Keywords:
  earth,
  fossil,
  geology
Asked by 782yttc52 to Anna, Hayley, Iain, Rebecca on 21 Jun 2015.
- Rebecca Jones answered on 21 Jun 2015:
  
  The oldest fossils are of cyanobacteria (bacteria which get their energy from photosynthesis) which are about 3.5 billion years old!

Question: How old are the oldest fossils on earth?