A foreign brick.
A square box. A special case is a cube or playing die.
A tent
All the large pyramids in Egypt, Mexico, etc are all rectangular pyramids. All have a square or rectangular base and four triangular sides meeting at a point. ■
If you asking where you'd find them in the real world - Binoculars and telescopes are two examples.
A cereal box or a t.v. [not flat screen] or a book.
A solid brick is a rectangular prism. (this one example of many)
A foreign brick.
roof
A building would be a perfect example. If you simplify the details of a building, it becomes a rectangular prism. If you specifically mean a "square" prism, that would be a cube, an example of which would be a Rubik's Cube or a few dice.
Roof of a house
tent
find
A square box. A special case is a cube or playing die.
A basic camping tent, a house roof, and the iconic Toblerone box.
It would be bad if they used a rhombicosidodecahedron. That is a real thing, not kidding.
stuff