A groundbreaking study published in *The Seismic Record* has mapped the deformation of Earth's deepest mantle, revealing that ancient tectonic plates buried thousands of kilometers underground are affecting its structure. Researchers, led by Jonathan Wolf from the University of California, Berkeley, utilized an extensive dataset of over 16 million seismic waves from 24 global data centers. This research confirms long-held theories about mantle flow and provides a global perspective on deformation patterns. The analysis showed that most deformation occurs in regions where these ancient slabs are believed to reside, highlighting a connection between deep mantle deformation and subducted tectonic plates. By studying seismic anisotropy, scientists can identify areas of the mantle that have been stretched or distorted. The results indicated that anisotropy was present in about two-thirds of the regions examined. Wolf emphasized that while some areas lacked detectable signals, it does not mean they are free of deformation, as current methods may not capture weaker signals. This study opens new avenues for understanding the dynamics of Earth's interior and the complex interactions occurring at great depths.