Here's why:

* Microbes are microscopic organisms. This includes bacteria, archaea, fungi, protozoa, and some types of algae.

* All living organisms are made up of cells. This is a fundamental principle of biology.

* Cells are the basic unit of life. They contain the machinery necessary for growth, metabolism, and reproduction.

So, whether it's a single-celled bacterium or a complex fungus, all microbes are fundamentally composed of living cells.