What was One of the earliest forms of life?

The earliest lifeforms on Earth were germs and bacteria, and they are very different from hat they are today because many of them have mutated and changed to fit what has happened over time. We have been able to minimize, if not eradicate, sicknesses caused by these lifeforms, and that has caused changes in them as well. Basically, they have modified themsleves to fit the environment or conditions around them. From what they were when they were first on Earth, compared to what they are now, there has been a huge change.