Mystery Egg

I found this egg outside in our yard yesterday while I was racking and cleaning up the gardens. It was smaller than any egg I have ever seen for sale in a store and the fact that I have never seen white eggs in the shops here (really stinks for dying eggs at Easter!), tells me this egg was someone's home for awhile.

I tried to give you an idea of size by comparing it to this little leaf. Although, the leaf looks a bit big in the picture, so that didn't really work very well! Anyway, the way the egg was cracked was strange as well, as if something had popped out. I'm not very knowledgeable in this department...
Any thoughts of what might have hatched from this wee egg? A bird, snake, crocodile...?