Comment by gchadwick

Certainly no expert here but if you take the original video and replications at face value it does exhibit strong diamagnetism at room temperature. Superconductors are diamagnetic due to the Meissner effect at their superconducting temperature. This would mean LK99 is a superconductor at low temperature and separately be strongly diamagnetic at room temperature (no Meissner effect if it's not super conducting). Would that be unusual?