Defects, essentially locations in a crystal where the perfect arrangement of atoms is disturbed, are inherent in materials, and play a key role in their function. As they have been studied for so long, the discovery of new types of defects is rare. In recent work in IRGs 1 and 2 a completely new type of defect has been found in a class of complex oxide materials called perovskites, specifically the compound NdTiO3. This new defect is a “line” defect formed by a long local region of the crystal that rotates from the typical ordering pattern, as shown in the figure. This discovery was enabled by combining state-of-the-art synthesis methods with atomic resolution electron microscopy and complex computations, requiring collaboration between three MRSEC research groups with complementary expertise. One potential application lies in engineering such line defects to create atomic-scale “tunnels” for the flow of electrons or atoms.