Boiled penguin eggs have transparent whites.

Penguin egg whites turn clear when boiled. This is because the glycoprotein that would typically make chicken eggs white, ovalbumin, is less present in penguin eggs; there is more of another glycoprotein, called penalalbumin.

This makes the egg more cold resistant. In their natural state, boiled penguin eggs are a pale greenish-white on their coating, and have a pear shape to them. They’re approximately 12cm long and 8cm wide in size.