Why Teapot in 3Ds Max?

Apart from the fame the teapot is a good object to use for test rendering and benchmarking when its shape with a spout and handle allows for self-shadowing and the curved surfaces are good for reflection tests, and this is the reason it can be found in 3DS Max to this day.

Why did Martin Newell choose the teapot?

It was an auspicious choice: The curves, handle, lid, and spout of the teapot all conspired to make it an ideal object for graphical experiment. Unlike other objects, the teapot could, for instance, cast a shadow on itself in several places. Newell grabbed some graph paper and a pencil, and sketched it.

Why is the Render icon a teapot?

It is a mathematical model of an ordinary teapot that appears solid, cylindrical, and partially convex. A teapot primitive is considered the equivalent of a "hello, world" program, as a way to create an easy 3D scene with a somewhat complex model acting as a basic geometry reference for scene and light setup.