Polymetallic (Manganese) nodules occasionally turn up in mineral collections around the world of people like Fioravanti who had academic contacts. This would have been collected on some oceanographic expedition to a deep ocean vent or "smoker," most likely. Composed of manganese, nickel, copper, cobalt, iron, silicon and aluminum in varying percentages, these were harvested off the ocean floor. This particular nodule very much resembles a scoria bomb, with very fine vesicles throughout, many microcrystals, and a coarsely-layered construction. It is complete all around and masses surprisingly light, at 500 grams.