Chickens for example, or snakes, or even ostriches all share the egg as a common first home. Eggs come in many different sizes, but they are always egg-shaped. Anything else is a ball, and will not hatch no matter how long you sit on it.

Eggs are notoriously bad for ball-games, having neither the shape nor the structure to withstand being hit with sticks, being bounced on concrete, or being kicked with studded boots.

They are also very bad at spinning on their end. An egg can only be spun on its end on one day of the year; the Spring Equinox. Or perhaps it's the Autumn Equinox. This might have something to do with the way the sun lines up with the earth, or may alternately have intimate associations with astrology. Or maybe it's astronomy? Or neither. Whatever.

When spinning the egg, nothing happens, and after spinning the egg you are left with a deep feeling of disappointment that, on the one day in the year that you are actually able to spin an egg, you do, and nothing happens.