I think more salient examples that make this question hard are not going to be borne out of trying to come up with something increasingly abstract. The more puzzling cognitive objects to explain are when you apply unphysical transformations to obvious objects... like taking a dog and imagining it stretched out to the length of a football field. Or a person with a torus-like hole in their abdomen. But these are simply images in the brain. That the semantic content of the image can be interpreted as strange unions of other cognitive objects is not a reason to think that the cognitive object itself isn't physical.