Don't worry, this UFO isn't here to abduct you. Not unless you're tiny, and ferromagnetic. It's just a centering magnet to ensure good alignment for charging.

Looking at this Oreo cookie of a charger, we find the inductive coils in the lower section, and a dense weight in the upper portion.

Speaking of density, here's a map with COLORS.

This fancy 3D graph shows the density of the charger's internals, with higher points representing greater density. That dark red semi-circle is the magnet, while the yellow indicates the charging coils.