The oldest known fossils are prokaryotic.
Fossils can be formed by:MummificationPetrificationDesiccationRelated question on Answers.com:How are fossils formed?
Stromatolites.
The oldest humanoid fossils were all found in Africa.
In undisturbed strata, the oldest fossils will be the deepest from the surface.
The fossils that are further up among the layers would be newer because they were formed before the others.When fossils are further down in the ground they are older because they had been covered up longer in time.
Yes, the phylum porifera contain some of the oldest organisms because they are formed from fossilized, tiny sea organisms which were the precursors to modern life.
by fossils
The oldest micro fossils are comprised of carbon. This is because they have been in the ground a very long time and it compresses the materials into carbon.
The oldest known fossils are up to 3.5 billion years old.
Africa
fish