The universal ancestor likely would have been an aquatic organism that had a permeable membrane, distinct organelles and was able to process energy from light. It is thought to have contained the original genetic code for all branches of modern life.
Termed LUCA by scientists, the last universal common ancestor is believed to have been a single-celled organism whose DNA functioned as the foundation for all forms of life. Modern research additionally claims that LUCA was a composite of organelles that developed into the separate domains of bacteria and archaea – independent life forms from which multicellular organisms eventually evolved. Its seawater habitat was rich in protein and alkaline fluid, allowing the cell's membrane to absorb energy through light, form organelles and to diverge into these two domains.