The first living organisms on Earth were **prokaryotic microorganisms**, which appeared around **3.5 to 4 billion years ago**. These early life forms were simple, single-celled organisms, and most likely **anaerobic** (able to survive without oxygen), as Earth's early atmosphere had little to no oxygen.

The first living organisms on Earth were **prokaryotic microorganisms**, which appeared around **3.5 to 4 billion years ago**. These early life forms were simple, single-celled organisms, and most likely **anaerobic** (able to survive without oxygen), as Earth's early atmosphere had little to no oxygen.

### Types of First Living Organisms:

1. **Prokaryotes (Bacteria and Archaea)**:

   - The earliest life forms are believed to have been **prokaryotes**, organisms without a nucleus or complex internal structures. They likely thrived in Earth's primitive oceans.

   - **Archaea**, a domain of life distinct from bacteria, are thought to be among the first organisms, adapted to extreme environments such