The World of Microfossils
When the term "fossil" was first introduced, it incorporated not only remains of plants and animal, but also stones, minerals, and artifacts. The definition has been modified to its present state.
Fossils: Remnants of prehistoric organisms, including the traces of their activities.
Microfossils are just a further classification of fossils.
Microfossils: All fossils which can be examined only under a microscope, irrespective of their systematic classification.
Bacterial microfossils found in Geiseltal lignites were at least 50 million years old.
Examples of microfossils include foraminifers, radiolarians, ostracods, conodonts, otoliths, silicoflagellates, diatoms, coccoliths, mites, bacteria, pollen and spores.