3 Answers
http://www.abc.net.au/science/articles/2012/05/01/3492086.htm
" So one reason that eggs have an asymmetric tapered oval shape is that if you nudge them, they'll come back to you. They'll sweep out in a circle around the pointed end, and come to a stop with the pointed end facing uphill. In fact, the eggs of birds that have their nests on cliffs are more oval than the eggs of birds that nest on the ground. This means the 'more-oval' eggs of these cliff-nesting birds will roll in a very tight little circle, and be less likely to roll out of the nest — and off the cliff.
Another reason for eggs to be egg-shaped is that they fit together quite snugly in the nest, with only small air spaces between them. This means the eggs radiate their heat onto each other, and keep each other warm. And of course, you can fit more eggs into the nest.
Yet another reason that eggs are tapered is so that they can get pushed out of the hen. It sounds intuitively wrong and extremely uncomfortable, but eggs are laid with the blunt end coming out first, followed by the tapered end. In fact, the physics of pushing-an-egg-out tells us that eggs have to come out blunt end first.
I'll explain with an example. If you've eaten cherries, you'll have come across the pip or stone inside the cherry. That pip is tapered on each end. Think how easy it is to squeeze a tapered cherry pip between your fingers, and squirt it a metre or two. At the other extreme of things, think how hard it would be to squirt rectangular dice anywhere, if you just squeeze them between your fingers. It would be impossible."
http://www.abc.net.au/science/articles/2012/05/01/3492086.htm
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