If the deep mantle anomalies are indeed remnants of Theia, what compositional evidence might confirm this link by comparison with other extraterrestrial samples?

Isotopic signatures similar to lunar samples brought back by the Apollo missions

The greatest potential confirmation for the Theia hypothesis lies in chemical forensics comparing the deep anomalies to known materials from the Moon-forming event. The material ejected into orbit to form the Moon was a mix derived from both Earth and Theia. Therefore, if the massive structures buried in the lower mantle are indeed Theia's preserved corpse material, they should exhibit isotopic signatures—such as specific ratios of tungsten or other refractory elements—that align closely with the chemical composition found in lunar samples collected during the Apollo missions. Such a match would strongly suggest the anomalies share a common genesis with the debris disk that created our satellite, thereby distinguishing them from material that resulted purely from Earth's internal differentiation processes.