when I was playing SA2 I went to the hero garden and my hero chao changed into an egg. please tell me the reason. thanks.
It reincarnated. If a chao's been treated well, it will reincarnate around age five. When it rehatches, it will be a baby again, only with 10% of its original stats from the start. Reincarnating your chao can make it stronger and lead to it becoming a Chaos chao.

~ Crazy C Lea