Protista are eukaryotic and can be unicellular or simple multicellular. They reproduce sexually or asexually. Important examples of protists include the organism known as Plasmodium (which causes malaria), Amoeba and Euglena. There are two major groups of protists which include the Protozoans, whose cells are similar to animal cells in that they do not have cell walls and the plant-like cells which do have cell walls and are similar to algae.
Euglena an example of a protist.
Diatoms from Antarctic sea ice.