What energy source possibly created the building blocks of life during the early parts of the creation of life on Earth?

These early cyanobacteria were the first oxygen-producing, evolving, phototropic organisms, and they were responsible for the initial oxygenation of the Earth's atmosphere, as they produced oxygen while sequestering carbon dioxide in organic molecules during the period from 2.7 to 2.2 billion years ago.

the animal that would be cutest if scaled down to the size of a cat? elephant