Core

Slowly the planet cooled, it's outer part first, its crust, and began to resemble the solid land formations that paved the way for eath's current form. This fragile layer, like an egg's shell, floated on an inner sea of liquid magma. Volcanoes and eruptions dotted the landscape with neon magma and clouds of steaming gases way more often than today.

Now the earth, still young and hot, floats and moves along the magma surface, subject to the powerful convection currents that churn below. Land masses crush together and something's got to give, sending crust plunging downward and melting back into the core: a subduction zone. Magma rises from the interior and becomes new land in areas where the crust is pulling away from each other.

I thought of it like a water balloon containing its liquid interior, holding together its heated core, delicately floating on it magma ridden interior.