Slime: A Book Review

By Celeste Schantz

Algae. When you read the word, what pops into your mind? A bright green ring of slime around an outdoor drain? Dark green fuzz obscuring the glass of a fish tank? Pea-soup scum blanketing a pond in midsummer?[i]


Ruth Kassinger’s lively and accessible new book on Slime conjures these images and many more, taking readers on the organism’s 3.7-billion-year journey from the very first bacterium in existence to algae gasoline of the future.


Algae, Kassinger says, are a hidden part of our lives They thicken lotions, gel our toothpastes, and prevent ice crystals from forming in our ice cream.These photosynthetic organisms blanket our oceans in a dense but invisible six-hundred-foot-thick layer of Sargassum.

“If all algae died tomorrow,” says Kassinger, “then all familiar aquatic life—from tiny krill to whales—would quickly starve.” And at least 50 percent of the oxygen we inhale is made by algae, a sobering thought as our oceans continue to warm and acidify. Algae can kill us with its blooms. Its neurotoxins have caused seagulls to suicide-dive into the roofs of coastal village homes (think Hitchcock’s The Birds.)

But in this time of global warming, algae can also provide nutritious food, oxygen, biofuel and other lifegiving byproducts for a starving planet.


From prokaryotic cyanobacteria (blue-green algae) a tenth of the width of a human hair to giant kelp forests rising 150 feet tall in the ocean, the future of algae will in part determine the future of all living things on earth. Not just the scum of the earth, Algae are intrinsic to life as we know it.

And Kassinger’s Slime should be in everyone’s TBR pile.



[i] Slime: How Algae Created Us, Plague Us, and Might Just Save Us, Ruth Kassinger, Houghton Mifflin Harcourt 2019, Introduction.

Photo Credit: Crescent Bay Beach, United States by Shane Stegner