Yup, some steel does, isn't it interesting that England continued to make those big honker pennies... They also spit out silver and foreign stuff.
I didn’t read to the end, but I am with the ‘plated’ members. A spectrometer would bear this out, but the visual evidence supports the diagnosis. People do funny/strange things out of boredom or curiosity. This appears to be one of them. I recall nickel plating LWCs, some came out shiny and others dull. Dull worked well with replating, sort of like etching before copper flashing. Take it to a shop with a spectrometer.