 Chalmers’s description expresses structuralism about physics vividly. But his claim that physical theory characterizes its basic entities only relationally could be challenged. Shape is usually counted among an object’s non-relational properties (Stoljar 2015). For example, contrast a ball’s sphericality, a non-relational property, with its tendency to roll when pushed, a relational property. So, if physical theory characterizes its basic entities partly in terms of their shapes, then Chalmers’s claim might seem doubtful.