If you're in the need for some kind of magical artifact of magic for your setting, consider Fresnel Lenses which are used in lighthouses:
These things are Alive.
Fun fact:
They used to float (and some still do) on a bed of MERCURY.
It's a means of reducing friction during rotation, and one of the lighthouse keepers' jobs used to be cleaning and straining impurities from the mercury.
So yeah that probably did contribute to erratic behavior more than a few times.