From debut author-illustrator Tom Sullivan comes a surprising and innovative picture book that is both a light introduction to the science of evolution and a tribute to every child's power to dream big.In I Used to be a Fish, a boy is inspired by a pet fish and fueled by imagination to tell a whimsical version of his own life story, which mirrors the process of human evolution. Children--and adults--will love the Seussian absurdity of this tale.The book features a timeline of life on earth and an author's note, which includes important facts about evolution.