The A egg is an extremely rare item on tinkatolli. They can't be traded, and they were an item for closed betas only to find. It left the island on October 2 2011. It was the fourth of the five beta eggs.
Before being picked up, the golden beta egg looked just like glass. This made it that much harder to find. And to make it yet harder, it was in a different place for everyone.
Many players who recieved the A egg put it in their tinkapads. When it is in the bag, it is in the unusuals section.