This reminds me of something I've always thought that Toph – spoiler about Avatar: The Last Airbender – should also be able to blood bend since she created metal bending and the blood is full of iron.
There is a scene in one of the X-men movies where Magneto escapes a completely non-metallic prison by extracting iron from a guard's body. I initially thought that Raven had injected him the previous day with something to increase his iron content. But realized later that she had injected metallic iron as a suspension.
That aside, you don't need ferromagnetic substances for it be manipulated by magnetic fields. Anything conducting can be moved around by fluctuating magnetic fields. Even non-conducting paramagnetic or diamagnetic substance will eventually respond to very high strength magnetic fields - just not at the 'feeble' strengths of an MRI machine's superconducting magnets. Here is something I collected previously on the same fun topic: https://phanpy.social/#/fosstodon.org/s/111504060685437481?v...
