Coralline Algae Under the Microscope

Unlike the green, leafy algae we're used to seeing on the seafloor, coralline algae has a hard crust—which you can see here at the molecular level in a photo from a scanning electron microscope. Each coralline algae cell builds a limestone wall around itself, creating a honeycomb-like structure. As layer upon layer of algae grow over one another, they form an ever-thicker crust that acts as a cement, holding coral reefs together. Read more about coralline algae on coral reefs.