Usb mount

I’m using a board ( that allows to connect mSATA disk as Usb device to rpi.
The files on disk show up in /media/ folder directly (and in the root of Usb samba mount, samba config maps Usb folder to /mnt/usb).

I’m trying to figure out how it is mounted as disk does not show up as mounted.

it shows up in /dev/disk/by-id, but not in /dev/disk/by-uuid
the disk (sda) is listed in lsblk, but there is no mount listed there
I can see other Usb mounts there under /media/[name of the mount]

and parted sees the disk, but partition table is unknown there

how is it, actually, mounted to the /media/ folder?

because I am thinking about something similar, have you finally got it running?
Thx in advance, regards Axel

in addition @phwp:

I’m wondering how files on the disk can show up if the disk is not mounted?