-Both mitochondria and chloroplasts have bilayer membrane envelopes, something not found in other organelles, which gives another clue to their origins as autonomous prokaryotes.

-Meanwhile, the genome of the chloroplast (coming from the DNA chromosome within the Stroma) resembles a significantly shortened Cyanobacteria genome, with the missing pieces of the genome being found encoded in the nucleus of the cell.

-In some algae, like heterokonts, the chloroplasts have 3 or 4 membrane layers, meaning these eukaryotic organisms engulfed other eukaryotic cells containing chloroplasts and evolved that way.