Alien Data Disk

My Grandfather recently died and when we were sorting through his old air force stuff I found this thing. It is solid black very dull metal with precision cut geometric shapes. The number at the top was etched in by someone later because it is not as well cut into the metal as the shapes. It weighs about five pounds.

When he showed it to me when I was younger he always called it the "Alien data disk" (hence the name), but told my mom when he thought I wasn't listening that it was an "interfac