There's probably a fifth layer. (forplayday/iStock/Getty Images) NATURE Scientists Detect Signs of a Hidden Structure Inside Earth's Core TESSA KOUMOUNDOUROS4 MARCH 2021 While most of us take the ground beneath our feet for granted, written within its complex layers, like pages of a book, is Earth's history. Our history. Now researchers have found more evidence for a whole new chapter deep within Earth's past - Earth's inner core appears to have another even more inner core within it. "Traditionally we've been taught the Earth has four main layers: the crust, the mantle, the outer core and the inner core," explained...