Yep, here was the explanation in the email I got from a friend.
@unknownuser said:
It's a hard disk drive back in 1956... with 5 MB of storage. In September 1956 IBM launched the 305 RAMAC, the first 'SUPER' computer with a hard disk drive (HDD). The HDD weighed over a ton and stored a 'whopping' 5 MB of data.
Do you appreciate your 8 GB memory stick a little more now?
And if you could not read TIG's post...
@tig said:
it's an IBM 305 RAMAC.
That central cylinder is a hard drive. IBM introduced the hard drive (RAMAC) in 1956; it stored 5Mb [that's Mb NOT Gb !!!] in an enclosure the size of a big refrigerator, and cost ~$150,000. 1Tb now costs ~£300 !!! So we now have ~10,485,760 more space per dollar after 50+ years of development: it also fits in a much smaller volume...