dd if=/dev/rdisk12 of=/dev/zero (OT, since macOS)

Hi co-readers,

excuse me for coming up with a non FreeBSD question but I'm sure many "also macOS" users are here.
I got an SSD external drive today from China. It's supposed to have 10TB and has the name "SEAGATE" engraved on the cover which I haven't opened
yet, also because it's clipped together - no screws.

Anyway, I tried


# dd if=/dev/rdisk12 of=/dev/zero

on it (in a macOS terminal window.

I'm getting 

$ sudo dd if=/dev/rdisk12 of=/dev/zero bs=512
Password:
dd: /dev/rdisk12: Invalid argument
0+0 records in
0+0 records out
0 bytes transferred in 0.000036 secs (0 bytes/sec)
$ 

also without the bs=512 not any better.

An ideas what might be wrong?

--
Christoph