Does anyone want to help with research?
What did you have in mind, it's something I need to revisit but if I recall, scientists have done this already by studying earthquakes and how they pass through the earth and shadow zones created by the core.
I think the current theory (probly not up to date) is that a large chunk of the core is crystallized iron.
If I remember correctly, it's a nickel iron alloy, with a solid inner core and a liquid outer core.
I think the film, The Core, has a scene there.
Please, don't ever mention that movie again
I am unsure what is on the lower layer of most flat theories, sorry
I think the current FE stance is that it's unknown what's underneath.