Learn the Layers of the Earth

Have you ever cut open a golf ball to see what was inside? Did you name all your Russian nesting dolls? Have you ever tried to recall all the ingredients in a seven-layer dip? Were you obliged to learn the parts of a cell or an eyeball in school? Of course you did. And they all happen to come back again when we get a good look at the layers of the earth below us.

Seems plausible to me. Since you were in school, they've kept adding layers, or rather, they keep labeling new layers let's say, and it's hard to keep up. After all, no one has been to those layers to witness their makeup. Or get a taste of that nougat. It may as well be completely made up for all we know. I can't think think of anyone better to make those layers up than Randall Munroe at xkcd. ​

-via Nag on the Lake 

As an aside, my father was both a geology professor and a golf coach. More than once, probably more than I know, he would cut open an old golf ball to demonstrate the earth's layers. The dimpled vinyl was the crust, the rubber band majority of the inside was the mantle, and the liquid-filled rubber ball at the center was the core. Until he got hold of some foreign-made golf balls that had all manner of garbage inside, then he gave up on that idea. 

(Top image credit: Gohar7)