1. All living organisms are composed of one or more cells.

2. The cell is the basic unit of structure and organization in organisms.

3. All cells arise from pre-existing cells.

Therefore, anything that doesn't fall under these three points is not part of the cell theory. For example:

* Cells are the smallest unit of life: While cells are the smallest unit of life that can function independently, this is a consequence of the cell theory, not part of it.

* Cells are all the same: Cells come in many shapes and sizes, and they have specialized functions.

* Cells are complex structures: This is true, but not a fundamental principle of the cell theory.

* Cells are always visible with a microscope: Many cells are too small to be seen without a microscope, but even those visible to the naked eye still adhere to the principles of cell theory.

Let me know if you have more questions!