tent
Some of the pyramids in Antarctica resemble a triangular pyramid.
stuff
A pencil.
The Equator is a real world example, being the circumference of the Earth.
roof
Roof of a house
tent
A tent
Pup tent or lean-to
A real life example is a Toblerone chocolate bar which is in the shape of a triangular prism.
If you asking where you'd find them in the real world - Binoculars and telescopes are two examples.
Some of the pyramids in Antarctica resemble a triangular pyramid.
any box of tampons
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 square box. A special case is a cube or playing die.