Angry Birds: The Golden Eggs

In Angry Birds, there is a thing called golden eggs.
These eggs will unlock bonus levels that you can do.
Some levels are chain reactions,
and some are just like normal levels.
Golden eggs are very hard to find though.
Sometimes they are in plain sight,
while for others you have to do stuff to make them appear.
Also, new golden eggs will be shining.
That's the golden eggs.