These T-shirts celebrate the Planarian Anatomy Ontology (PLANA), a controlled vocabulary of Schmidtea mediterranea anatomical terms that are annotated with information (definitions! images! papers!), and the relationships between them (part of, develops from). The shirts depict the idea of nesting relationships related to scale and development in their logo on the front, while the back design represents all the anatomical terms (nodes shaped like planarians)and how they relate (lines). You can check out the PLANA here.