It's impossible to say for sure what the very first living organism was. Scientists have different theories about what life looked like in its earliest stages. However, the prevailing scientific consensus is that the first life forms were likely single-celled organisms that were very simple in structure. These organisms are thought to have emerged from non-living matter through a process called abiogenesis.

Here's what we know and some leading hypotheses:

* Early Earth's Conditions: The early Earth was a very different place than it is today. The atmosphere was very different, lacking oxygen, and the environment was harsh, with intense volcanic activity and bombardment by meteorites.

* RNA World Hypothesis: One popular hypothesis is that life began with RNA, not DNA, as the primary genetic material. RNA has a simpler structure than DNA and can act as both a carrier of genetic information and an enzyme, potentially leading to the evolution of more complex life.

* LUCA: The Last Universal Common Ancestor (LUCA) is the hypothetical organism from which all currently known life on Earth descends. Scientists believe LUCA was likely a simple, single-celled organism that lived in extreme environments.

* Hydrothermal Vents: One theory proposes that life arose near hydrothermal vents on the ocean floor, which release chemicals that could have provided energy for early life forms.

* "Primordial Soup": Another theory suggests that life originated in a "primordial soup" of organic molecules that formed in shallow pools of water on the early Earth.

It's crucial to remember: We're still trying to understand the origins of life, and it's a complex and evolving field of scientific research.

To sum up: We don't know exactly what the first living organism was, but we have many exciting theories and ongoing research to help us understand the fascinating journey of life on Earth.