Surprised I didn’t feature one of these earlier. A Utah teapot, ray-traced. From Wikipedia:
The Utah teapot or Newell teapot is a 3D computer model which has become a standard reference object (and something of an in-joke) in thecomputer graphics community. It is a mathematical model of an ordinary teapot of fairly simple shape, which 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. Many programming libraries will even have functions dedicated to drawing teapots.
The teapot model was created in 1975 by early computer graphics researcher Martin Newell, a member of the pioneering graphics program at the University of Utah.
One place you might have seen this: as an Easter egg in Windows’ 3D Pipes screensaver.
Due either to this or to the teapot model being somewhat old, these teapots go for quite a bit on eBay (though apparently they have begun to be 3D-printed, from the renders, ouroboros-like).
(TEAPOT3.GIF, retrieved via the GIF Galaxy shareware CD (1993) via cd.textfiles.com. Artist credit appreciated.)