Object-based learning is an approach that aims to foster observational skills and sensory awareness. Paradoxical plant objects that do not lend themselves to all-too-easy explanations and interpretations can be used to practice the search for ecological explanations and the formation of evolutionary hypotheses. They can be the basis of particularly fruitful and rewarding learning experiences. "Gleditsia triacanthos," the honey locust, is a commonly planted ornamental tree. It exhibits striking structures of defense against -- and fruit that point to a mutualism with -- large animals. These structures, possibly developed in coevolution with Pleistocene faunas, invite a discussion of the complex, neither fully antagonistic nor fully mutualistic, relationships between plants and animals.