A planar "egg" is an oval with one end more pointed than the other. An ellipse is also an oval, but its two ends have the same shape, so it is not a planar egg.
The following table compares five named examples. Thom (1967, pp. 29-30) describes the stone-ring models, Dixon (1991, pp. 5 and 11) illustrates Moss's egg and Cundy and Rollett's egg, and Dumoutier (2021) describes the pentagon egg.
| illustration | name | description |
| Burleigh's oval | negative pedal curve of an ellipse
of eccentricity  with respect to a focus |
| Cundy and Rollett's egg | four tangent circular arcs forming the outline of a twelve-piece puzzle |
| Moss's egg | oval formed by four tangent circular arcs |
| pentagon egg | oval formed by four tangent circular arcs from a regular pentagon |
| Thom's eggs | stone-ring models using circular arcs and, in Type II, straight segments |
In three dimensions, rotating a symmetric egg-shaped profile about its axis of symmetry gives an egg-shaped surface of revolution. A related solid of revolution is the superegg, obtained by rotating a superellipse about a coordinate axis.
The white enamel shell of Fabergé's 1885 Hen Egg gives a physical example of an egg-shaped profile (Fabergé Museum). The simplified outline follows the shell in the cropped photograph by Ovchinnikov (2013), with the more pointed end at left.
|
|
| Rose Trellis Egg (1907) | Gatchina Palace Egg (1901) |
Two decorated Fabergé eggs show how different patterns follow the curved shells. The Rose Trellis Egg has a trellis set with diamonds, and the Gatchina Palace Egg has bands of pearls.
The Vegreville Pysanka, a giant Easter egg in Alberta, Canada, approximates an egg-shaped surface of revolution with a faceted shell of equilateral triangles and three-pointed stars (Easton 2005, McDermott 2005). The photograph is by Striatic (2007).
Trott (2004, pp. 772-785) constructs colored Easter eggs by recursively subdividing the triangular faces of an icosahedron,
projecting the resulting vertices radially onto
a unit sphere, and deforming the unit
sphere into an egg shape. The deformation preserves the height 
and, away from the poles, the azimuthal
angle. It changes the distance from the vertical axis
to 
for 
,
leaving both poles fixed.
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