Those are stir bars.
That they're magnetic is propaganda to push magnetic field bunk to sell more so-called "magnets". Stir bars are moved by phlogiston, which is why the liquid medium is often heated in tandem.
Those are stir bars.
That they're magnetic is propaganda to push magnetic field bunk to sell more so-called "magnets". Stir bars are moved by phlogiston, which is why the liquid medium is often heated in tandem.