I believe that the case with Wasilevski is that his message have been probably perverted by "popular" explanation - probably what he meant is that extremely well magnetized samples have origins different from just being cooled in Earth magnetic field.
Concerning the knowledge that ancient iron (whether in pottery, iron deposits or special spherical boxes lying on the ocean's floor) is magnetized alongside the Earth magnetic field at the time of the iron sample's cooling period is a well known fact, avoiding "real" papers I would bring your attention to:
"Magnetite is magnetic because its molecular structure has allowed it to retain the alignment of particles caused by the Earth's magnetic field during its formation millions of years ago. When heated to high temperatures magnetite loses its natural magnetism. "
"Finally, a fourth bit of evidence also favors the idea of plate tectonics, although here the data aren’t as robust, their implications not as clear. This evidence is supplied by paleomagnetism—the study of ancient magnetism. Everyday experience tells us that iron is magnetic; in fact, any metal containing even small amounts of iron ore is usually magnetized. However, when iron is heated to temperatures ~1000 K, it loses its magnetic properties as individual atoms jostle freely (which is why magnetic thermometers often fall off the side of a roaring wood stove). Hot basalt—the dark, dense stuff of volcanoes—impregnated with traces of iron and upwelling from cracks in the oceanic ridges, is thus not magnetic. As the basalt cools, magnetism sets in as each iron atom effectively responds to Earth’s magnetic field like a compass needle. When the basalt solidifies to form hard rock shortly thereafter, it fixes the orientation of the embedded iron, since the iron atoms align themselves with the orientation of Earth’s field at the time of cooling. Accordingly, the ocean-floor matter has preserved within it a history of Earth’s magnetism."