Which type of microorganisms are known to be immobile?

Cocci are round-shaped bacteria that are generally immobile. Their spherical shape allows them to easily cluster together, but they do not have the structures, like flagella or cilia, that would enable them to move independently. This characteristic distinguishes them from other types of bacteria, such as bacilli (rod-shaped) and spirilla (spiral-shaped), which can possess means of motility. Viruses, while they can be active in terms of infecting host cells, do not have mobility in the way that living cells do, as they lack cellular structures entirely. Therefore, focusing on the immobility aspect, cocci specifically stand out as a type that does not exhibit movement on their own.