All land animals evolved from under the water. I would say fish and ammonites.
Stromatolites are one of the earliest known life forms; some fossils may date back 3.5 billion years - before Earth had any oxygen in it's atmosphere.
The earliest evidence of life on Earth comes from fossilized microorganisms that are approximately 3.5 billion years old. These microorganisms are simple bacteria-like organisms known as prokaryotes. They thrived in environments such as hydrothermal vents and shallow seas.
I cannot answer this question.
Cyanobacteria.
Cyanobacteria
cyanobacteria
The earliest ones still around are stromatolites, but there were lots of earlier life forms.
One example of a life-form in the Precambrian time was cyanobacteria, which are ancient photosynthetic bacteria thought to be one of the earliest forms of life on Earth. Cyanobacteria played a crucial role in the Great Oxygenation Event by producing oxygen as a byproduct of photosynthesis, which significantly altered Earth's atmosphere.
Longer Life Larger specialization
The prevailing theory of the origin of life on earth posits that it began in the oceans.
The earliest forms of life were microscopic autotrophs that lived in the great prehistoric oceans. Living under the water protected them from the deadly UV rays from the sun, as at this point Earth had not developed a suitable atmosphere. This is true everywhere but Kansas, where the earliest life forms were Adam and Eve. Zing!
The earliest lifeforms on Earth were likely single-celled organisms, such as bacteria and archaea. These organisms were simple in structure and relied on primitive forms of metabolism to survive. Over time, they evolved into more complex life forms.