In this paper, we intend to understand how the Platypus (Ornithorhynchus anatinus) is a paradoxical animal both for an epistemologist and for a science education researcher in science education. Firstly, we’ll expose the historical identification process of this animal. Second, we’ll analyze the content of three storybooks that can be presented to primary school pupils (aged 8-11). The history of the platypus is well known but it reflects many difficulties in morphology, anatomy and classification. Today, some paradoxical characters of the Platypus are investigated from a genetic, genomic or evolutionary viewpoint. But at primary school, is the Platypus, a curiosity and an exception, a good example to show some difficulties of description and classification in biology? In biology education, exceptions are often excluded while the popular science puts. At primary school, mediation is needed to explain classification to pupils. We chose three storybooks about The Platypus. Content analysis of these storybooks focuses the different ways characters classify the Platypus and what arguments they use. These fictional narratives underline the met failures when characters want to classify the Platypus: its similarities with mammals or birds constitute an obstacle to integration in a definite class.