ps What you might call a hot rock- I call a concretion. If it beeps- its metal. Mineralisation my balls.
sorry to sound so disrespectful, but thats my experience. Obviously the fields and the sea are different.
in the sea, when 2 metals lie together, the lesser sacrifices Itself and forms a concretion. It sounds like iron. Looks like a potato. that was inside
its all good.