Land that is not expanded will be unusable, to expand it, click on the sign in the middle of that land and pay the money or friend stones. Once you expanded land, the land will flash and turn into usable land. However, this only expands a sqaure of area. And each time you expand more, the price goes up.
There is unusable land that can't be expanded in anyway. For example: The sea, the mountains, and a tiny island.
Non playable animals
There are seagulls flying in endless circles, there are two flocks of them.