ELI5: Explain Like I'm 5

Poinsot's ellipsoid

Poinsot's ellipsoid is like an egg shape but it's made from a combination of circles. Imagine three circles placed in a triangle shape, like a pyramid, with each circle touching the other two. Then imagine that all three circles are flattened at the same time. This forms the shape of Poinsot's ellipsoid. The shape is useful in mathematics and engineering because it is easy to measure.