It’s the guts of 3.5" floppies, like these, they usually stored 720kB, then 1.44MB, but the latest versions (double sided) were 2.88MB.

The larger one at the bottom is from a 5 1/4" (orange in this picture, the bug daddy in the picture is 8", first type I used, with COBOL)

… and now you kids know where the “save” button icon came from.

Hear, hear.

As in, wha? Did you say something? taps cane on the floor