The cell that usually forms unicellular organisms is a prokaryotic cell.

Here's why:

* Prokaryotes are single-celled organisms that lack a nucleus and other membrane-bound organelles. They are simpler in structure than eukaryotic cells.

* Eukaryotic cells are more complex and have a nucleus, where their DNA is stored, as well as other organelles. While some eukaryotes are unicellular, most form multicellular organisms.

Examples of unicellular prokaryotes:

* Bacteria

* Archaea

Let me know if you have any other questions!