Exploring the Tolkien World

So I went hunting for accidental art...in my grandmother's house. (It was raining, cold and dark outside.) I found this gem:

Can you see the peanut looking indent in the tile? Originally, all I saw was that peanut. Then I realized it kinda looks like a key hole, in which case it's probably a drawf-made door (which is obviously a work of art because these Tolkien's dwarves are master craftsmen and don't mess around with un-artistic doors). Also, Smaug's treasure is probably under my Grandma's house in South Jordan. NBD.