Egg pieces are found in any of the adventure's levels. There are three egg pieces every level, the player need to buy all the three pieces in order to finish the level and get the pet who just hatched from the egg. The first level's egg pieces cost 150$ each, but in every level they cost more than in the one before it, and the last level's egg pieces cost $99,999 each!
Though Egg pieces aren't found in Time Trials, the player can buy a full egg with one of his pets (chose randomly), that pet will help the player in the Time Trial, Making the Time Trial the mode with the largest amount of pets allowed. In the Time Trial, the first egg cost 100$, the second cost 200$, the third cost 400$, the fourth cost 800$ etc.
Buying full eggs
The only way to buy a full eggs (New pets, not Time Trial full eggs!) is to buy the bonus pets, these are four bonus helpers, they aren't required but they help (Well, some of them). The problem with them is that they cost lots of shells.