Here's why that statement is incorrect:

* There are some very large cells. The largest single-celled organism is a type of algae called *Acetabularia*, which can reach several centimeters in length.

* Multicellular organisms are made of many cells. These cells can be quite large, like the nerve cells that run the length of your spinal cord.

* Size is determined by function. The size of a cell is determined by its function and the amount of resources it needs to carry out that function. Small cells are efficient at exchanging materials with their surroundings, while large cells need specialized structures to facilitate this.

So, while most cells are microscopic, there are some notable exceptions!