People, it is a spiral, not concentric circles, you can see the end/start point in the center (top-right-ish). I don't think any HDD platters or floppy disks have been laid out like that.
It does look like a floppy disk magnetic cookie but the two smaller holes are throwing me off. Did Twiggy disks have two index holes? I know they had two read head slots but I've never seen a picture of the bare media so I dunno if they had two index holes
