Egg.

I live in a two bedroom apartment on the 2nd floor of a three story building, and we have a little balcony that is separated from the living room by a sliding glass door. The other day I looked out through the glass door and saw something peculiar. There was a perfectly intact little bird egg, balancing ever so carefully on the narrow railing of the balcony.

 

I have no idea how it got there. One suggestions was that the mama bird landed on the railing and it was so hot that she laid an egg. I don't know....  The really strange thing is that it is still there, two days later.