I wonder if it is radioactive. :-) There was a brief flurry of selling various rare Russian military parts that had been scavenged from equipment that had been left behind in the towns around Chernobyl.<p>Probably not, and it is a fun artifact. I've got a number of PDP-8 core memories (actually in PDP-8's :-) which are much less rare. That said, if you're looking for a parent/child project, or just a fun project, you can make a bit of "core memory" out of a #2 iron nut, a couple of full bridges, and an opamp. We did this with the kids for a science project once and its a lot of fun. You get to learn about hysteresis, the inherent 'analog' nature of digital machines, and with careful planning you could impractically hide information in the spare nuts drawer in the garage :-).