Here's why:

* Gram-negative structure: Like many bacteria, cyanobacteria are gram-negative. This means their cell wall has a unique structure consisting of two layers:

* Outer membrane: A lipid bilayer containing lipopolysaccharides.

* Peptidoglycan layer: A thin layer of peptidoglycan, a complex polymer that provides structural support.

* Importance of the cell wall: The cell wall is crucial for cyanobacteria's survival. It helps maintain their shape, protects them from osmotic stress, and allows them to interact with their environment.

So, while their cell wall structure is different from plants, cyanobacteria do have a cell wall that is essential for their existence.