What type of organism is recognized for mostly being one-celled eukaryotes without a cell wall?

The identification of the organism as a protozoan aligns with what is understood about their characteristics. Protozoans are primarily unicellular eukaryotes, distinguishing them from many other organisms that are multicellular or prokaryotic. One of their defining features is the absence of a rigid cell wall, which allows them a high degree of flexibility and variety in their movement and feeding structures.

This characteristic is crucial, as it helps differentiate protozoans from fungi, which have a cell wall made of chitin, and from bacteria (both Archaebacteria and Eubacteria), which have a cell wall that typically contains peptidoglycan in the case of Eubacteria, while Archaebacteria have unique cell walls that differ from both traditional bacteria and eukaryotes. Thus, the traits of being unicellular, eukaryotic, and lacking a cell wall distinctly place protozoans in their own category among living organisms.