What if I told you that there's a hidden layer inside Earth's core that could reveal secrets about our planet's history and evolution? And what if I told you that scientists discovered this layer by listening to echoes of earthquakes that bounced back and forth between two boundaries multiple times? Sounds pretty cool, huh? In this episode of Earth SciShow, MrEarthGuy explores a groundbreaking discovery and what it means for our understanding of Earth's formation and evolution. We'll learn how seismology, the study of seismic waves, can help us probe the inner core and reveal its structure and properties. We'll also learn how the inner core is anisotropic, meaning that it has different properties along different directions, and how this anisotropy changes with depth and direction. And we'll learn how this anisotropy could be a fossilized record of a significant event in Earth's past that left a mark in its center. If you're curious about how our planet works and what secrets it hides, you don't want to miss this episode of Earth SciShow. Join us as we dive deep into the mystery of the ball within a ball within a ball at the heart of our planet.