Eli5: why are single cells so small? What’s the maximal size a single cell?

Question

What is the maximal possible size of a single cell organism? Why can’t a single cell be the size of a coin for example?

In: Biology

Answer 1

Look up the algae “Caulerpa taxifolia”, which is the largest known single-celled organism. It is, by definition, a single cell… Yet it can grow up to 12 inches in length!