How are there immortal cells?

Immortal Cells and the Community

When life was first created on this planet, natural death did not exist. “Primitive” single-celled organisms, such as bacteria, fungi, algae, and protozoa (e.g., amoebae and paramecia), were immortal.
Cells would grow until they reached a certain size; they would then divide, forming two daughter cells, which in turn would repeat the cycle. If unicellular organisms would age and die, then they would not provide a sustainable lineage. Think of it this way. The amoeba you see under a microscope today is technically the same cell as the original amoeba that existed more than three billion years ago.

Now that’s the kind of aging we can live with!