Is Earth's core lopsided? Strange goings-on in our planet's interior

Seismic waves generated by earthquakes travel through Earth's solid iron inner core faster in the direction of the rotation axis than along the equator. UC Berkeley scientists created a core growth model to explain this. To fit seismic data, the model predicts that asymmetric growth of the core leads to crystal movement that preferentially aligns iron-nickel crystals north-south. The model implies that the core is only 0.5-1.5 billion years old, a fraction of Earth's age.