2.5 million years.
1.5 billion years.
2.5 billion years.
3.5 billion years.
Microfossils are a type of fossil that has a size in the range of 0.001mm and 1mm, the study of which is referred to as micropaleontology. The study of such fossils requires the employment of microscopes - light or electron. The oldest microfossil of bacteria was found 3.5 billion years ago in Quebec, Canada.