The Eggs

The eggs are the bird's most desperate items they want in the game like Theme 1-8 's 'boulder". This is why the birds are angry because of the pigs who stole them. For every episode, there are three eggs other than Season's Greedings and Go Green, Get Lucky, which have one, Hogs and Kisses, 2.

Trivia

 * Eggs are the only indestructable object in the entire game (excluding walls and Rubber).
 * The Mighty Eagle can destroy eggs.
 * It is unknown if 2 of the 3 Eggs are the Boy and Girl Eggs from Hogs and Kisses.
 * On the Angry Birds Facebook page they posted a picture of a new hatchling bird out a an easter egg.