There is the crust, the outermost layer, where life flourishes.
Cool, solid, but moved by the inner layers.
And ultimately thin.
Then there is the mantle.
Warm, just under the surface, and of somewhat different nature than what lies above.
Pretty thick too. Takes a very long time to get through it, if that's possible at all.
And at last we come to the core.
Hot, molten, churning mass. Most mysterious too, since we haven't actually reached it (or have we?)
Who knows what secrets lie inside?
Not unlike the human being, eh.