Here's why:

* Structure: The cell wall provides structural support and protection for the prokaryote.

* Composition: It's primarily composed of peptidoglycan, a complex molecule unique to bacteria.

* Function: The cell wall helps maintain the shape of the cell, prevents bursting due to osmotic pressure, and provides a barrier against the external environment.

Note: While some prokaryotes, like bacteria, have a cell wall, others, like mycoplasmas, lack a cell wall.