We pulled the core memories into one conference room, and they really look good together.
This was the industry standard for electronic memory before DRAM and SRAM and Flash. Data was stored in the magnetization, or not, of each ring. It is a non-volatile memory, and relatively immune to radiation and soft errors, much like MRAM today.
Many of the rectangular patches are 4K bits. The early ones were woven by hand, and over the years the iron ring sizes shrank and became tightly woven into an electromagnetic fabric.