agedgruel wrote: What is that?
It's an external hard drive case with a couple brass weights and a thumb drive in it. The thumb drive pretends it's 1TB or 2TB, but probably has an actual storage capacity of a GB or two.
When you write something to it, it writes out to disk, and then starts rewriting at the beginning. But it "remembers" the file system you copied, so all your files are still "there" in directory listings and such.
Since most people would toss a couple files on it to "make sure it works" and then set up backups and ignore it, there's probably a lot of those floating around that people have no idea aren't actually holding their data.