No cells can be seen with out a microscope. These small organisms are microscopic, meaning can be only seen with a microscope.
Hope this helps you out! Good luck! :)
Answer:
Well the smallest objects that the unaided eye can see are about 0.1 mm long. Smaller cells can usually be visible with a light microscope. It is also possible to make out structures within the cell, like the nucleus, mitochondria, and chloroplasts. So in easier words, true, for some at least.