Chao Key

The Chao Key is an item that appears in Sonic Adventure 2 and Sonic Adventure 2: Battle.

Description
The Chao Key resembles a normal key, albeit blue and the top resembles a neutral Chao head, complete with a yellow ball. In the center of the "head" is a small image of a Neutral Chao's face.

Chao Keys are crucial to entering Chao World, as the player has to collect one as each character and take it to the end of the stage to unlock every character to play as in Chao World.