"Chickens Aren't the Only Ones" is a children's book by Ruth Heller that explores the concept of animals that lay eggs. The book highlights various creatures, including birds, reptiles, and fish, showcasing the diversity of egg-laying species in the animal kingdom. Through colorful illustrations and simple text, Heller introduces young readers to the idea that many animals, not just chickens, reproduce by laying eggs. This engaging approach helps children learn about biology and the different types of eggs, fostering curiosity about nature and the variety of life forms on Earth.