  We have studied LK-99 [Pb$_{10-x}$Cu$_x$(PO$_4$)$_6$O], alleged by Lee et al.
to exhibit superconductivity above room temperature and at ambient pressure,
and have reproduced all anomalies in electric and magnetic measurements that
they reported as evidence for the claim of LK-99 being an ambient-pressure,
room-temperature superconductor. We found that these anomalies are associated
with the structural transition of the Cu$_2$S impurity in their sample and not
with superconductivity.
