This is what my lava lamp looks like today: is it a snail? A cow? Or Behelzebub?
Why the lamp?
I use this to explain how convection currents are created in the atmosphere and in the mantle.
Why the horns?
Well this is quite exciting too as the wax in the lamp is behaving a little like an underwater volcano: like those on the Mid-Atlantic Ridge. The lamp cooled with a plume of wax making its way to the surface. Then when it was turned on again, two areas of weakness gave way and new bubbles of wax started making their way to the surface. The lamp was turned off before they could rise and they cooled down to form the horns.