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Children's Nonfiction Biology

One Tiny Bubble

The Story of Our Last Universal Common Ancestor

by (author) Karen Krossing

illustrated by Dawn Lo

Owlkids Books Inc.
Initial publish date
Oct 2022
Biology, Discoveries, History of Science, Prehistoric
Recommended Age
4 to 8
Recommended Grade
5 to 12
  • Hardback

    Publish Date
    Oct 2022
    List Price

Classroom Resources

Download Student Activity

Where to buy it


The wondrous true story of one tiny bubble that sparked all life on Earth—including yours

Meet LUCA—our Last Universal Common Ancestor, the itty-bitty organism that every unique life-form on Earth can be traced back to. This sprinkle-sized blob was formed from the dust of exploded stars, water, and a lot of heat. LUCA was a single cell that split into two, and these cells multiplied into more organisms that grew and changed. Over the billions of years that followed, the descendants of LUCA evolved into bacteria, mushrooms, sharks, fir trees, lions—and humans! All the extraordinary life on Earth began with LUCA, through a miraculous process that could also occur on other planets.

This vibrant and poetic informational picture book breaks down scientific concepts using simple, engaging language. Striking illustrations bring LUCA to life and reveal how readers are connected to one another, and every life-form on our planet, through one tiny bubble.

About the authors

Karen Krossing grew up in Thornhill, Ontario, with a family who loved to read. What could she do but read, too? Karen began to create stories when she was eight, and she continued this habit by writing poetry in high school. By then she was hooked on books, so she studied English at university then became a book editor and a technical writer. After Karen had kids, she began writing fiction for children and teens.

Karen uses writing to understand the world around her. In Take The Stairs, which was nominated for the Ontario Library Association White Pine Award, she writes about turning adversity into opportunity through the troubled lives of inner-city teens. In Pure, her latest novel, she explores sticky ethical questions about genetic engineering that today's teens will have to face in their lifetimes.

Karen is a writing instructor at Centennial College and she teaches an after-school writing program for kids and teens through Pegasus Studios in Toronto. She led workshops at the 2003 Canadian Children's Book Camp in Toronto and was on tour with TD Canadian Children's Book Week in 2005. Karen regularly conducts writing workshops and book talks at Canadian schools.

For a detailed interview with Karen, go to For contact information, please visit

Karen Krossing's profile page

Born in Hong Kong, Dawn Lo is an illustrator currently based in Vancouver, British Columbia, on the unceded lands of the Squamish, Musqueam and Tsleil-Waututh First Nations. Her work has appeared in the picture books Snow Song and The Rainbow Garden Is My Friend, as well as in stationery, greeting cards, public art installations, murals and more! Dawn aims to create works that are high-spirited and whimsical while retaining a certain degree of simplicity and humor. Most of her work is inspired by little everyday moments and personal multicultural experiences. When she is not drawing at her home studio, she works at the public library where she can surround herself with more books.

Dawn Lo's profile page


  • Winner, Crystal Kite Member Choice Award
  • Joint winner, Alcuin Society Awards for Excellence in Book Design, second prize
  • Commended, Best Informational Books for Younger Readers

Editorial Reviews

"This book squeezes millions of years of our past into a beautiful brief narrative of our last universal common ancestor ... In accessible and engaging illustrations, young readers will get excited about a tiny bubble and find plenty of fodder for story time ­discussion."

School Library Journal

"Krossing’s gentle, lyrical text explains a complex concept to young readers ... The simplicity of Lo’s vibrant, coloured illustrations not only suits the writing style but will also appeal to the book’s target audience."

Canadian Review of Materials

"A simple, matter-of-fact reminder that we are all connected."

Kirkus Reviews

"A vibrant, poetic, and impressively informational picture book that breaks down scientific concepts using simple, engaging language ... An extraordinary and unreservedly recommended addition."

Midwest Book Review

"An accessible and thought-provoking narrative nonfiction title to include in STEM collections for young elementary school-aged readers."

Children’s Literature Comprehensive Database

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