The oldest fossil evidence of eukaryotes is about 2 billion years old. Fossils older than this all appear to be prokaryotes.

It is probable that today’s eukaryotes are descended from an ancestor that had a prokaryotic organization. The last common ancestor of today’s Eukarya had several characteristics, including cells with nuclei and an endomembrane system (which includes the nuclear envelope).

oldest fossil evidence of eukaryotes — about 2 billion years old. biological carbon pump — process by which inorganic carbon is fixed by photosynthetic species that then die and fall to the sea floor where they cannot be reached by saprobes and their carbon dioxide…. plastid — one of a group of related organelles in plant cells that are involved in the storage of starches, fats, proteins, and pigments. cytoplasmic streaming — movement of cytoplasm into an extended pseudopod such that the entire cell is transported to the site of the pseudopod.