they are unicellular
Protists can be unicellular or in a colony of similar organisms but do not differentiate into tissues. They are eukaryotes.
Cells do the same, or very similar things, whether they are part of a unicellular organism or a multicellular organism; they have a metabolism, they consume nutrients and oxygen, they have waste products, etc.
Most of the unicellular organisms reproduces asexually.
Diseases do not cause unicellular organisms; unicellular organisms cause diseases.
Colonies of unicellular organisms can work together.
Yew , unicellular organisms are more primitive as compared to multicellular organisms .
Unicellular organisms evolved first; and from them evolved the multicellular organisms. But that leads onto another question as to why multicellular organisms evolved.
Stentors are indeed unicellular organisms.
Not all kingdoms include unicellular organisms. The kingdoms that do not have unicellular organisms include the plantae and animalia kingdom.
the examples of unicellular organisms are BACTERIA, CHLASMYDAMONAS, EUKARYOTES (EUKARYYOTA).
All modern organisms have unicellular ancestors. Even you.