Synonyms that are in the dictionary are marked in green. Synonyms that are not in the dictionary are marked in red.
Antonyms that are in the dictionary are marked in green. Antonyms that are not in the dictionary are marked in red.
This means that through a fateful endosymbiosis more than 1.45 billion years ago, the once symbiotic relationship between two independent organisms, resulted in a merger for the greater efficiency of the now mammalian cell.