The Sailor's Eyeball: How Large Can a Single Cell Be?

We think of cells as very tiny, whether they are part of a larger organism like humans, or a single unit like bacteria. But single cell organisms can grow large enough to be seen, or even as big as an eyeball. Meet Valonia ventricosa , a single cell algae that can grow centimeters wide. They are round and green and found in the ocean, which is why they got the name the sailor's eyeball. They are…