A 2023 study measuring up-to-fivefold reverberating PKIKPs (pee-kay-eye-kay-pees) gave evidence for this region's innermost anisotropic (an-ICE-uh-trop-eck) zone. Recent simulations predict this region has atoms such as oxygen and sulfur flowing in a superionic fluid, and a 2015 study found that this region contains 90 percent of the planet's sulfur. This region lies below a discontinuity named for either Keith Edward Bullen or Inge (10[1])Lehmann (een-guh LAY-mahn); (-5[2])Lehmann discovered this region by observing its reflection (-5[1])of certain body waves. About a millimeter of material is deposited (10[1])yearly onto this region, driving convection in the layer above this region (-5[2])to create a geodynamo. A (-5[1])2023 study discovered this region had stopped super-rotating, causing it to ■END■