Here's why:

* Coccus shape: Staphylococcus aureus is a spherical bacterium, fitting the definition of a coccus.

* Arrangement: It typically forms clusters resembling grapes, due to its tendency to divide in multiple planes.

* Significance: S. aureus is a common bacterium found on skin and in the nose, but it can also cause various infections, including skin infections, pneumonia, and food poisoning.

Other examples of cocci include:

* Streptococcus pneumoniae: A spherical bacterium that forms chains and is a major cause of pneumonia.

* Neisseria gonorrhoeae: A spherical bacterium that causes gonorrhea.

* Micrococcus luteus: A non-pathogenic, yellow-pigmented coccus found in soil and on skin.

Let me know if you'd like to know more about any of these cocci!