Algae. What springs to mind when you read that word? Maybe a seaweed forest? Maybe a pond covered in scum? Maybe a red tide? Those are all algae, and they can all change the world in different ways. This week Bethany Brookshire talks with Ruth Kassinger about the history, present and future of algae and her new book, "Slime: How Algae Created Us, Plague Us, and Just Might Save Us".

This episode is hosted by Bethany Brookshire, science writer from Science News.