How do I tell what's loading all these snap filesystems?

[Chris Green]

I've recently upgraded one of my systems to [x]ubuntu 19.10.

I know this pulls in chromium as a snap package and that there's no
alternative but there seem to be quite a lot of snap filesystems on my
system now.  Are *all* of these a consequence of chromium or is
something else using snap that I don't know about?  How can one find
out what's using a snap filesystem?

I see:-

    udev                3881      0      3881   0% /dev
    tmpfs                782      4       779   1% /run
    /dev/nvme0n1p2     48174  13822     31837  31% /
    tmpfs               3908    260      3648   7% /dev/shm
    tmpfs                  5      1         5   1% /run/lock
    tmpfs               3908      0      3908   0% /sys/fs/cgroup
    /dev/loop0            55     55         0 100% /snap/core18/1265
    /dev/loop1            45     45         0 100% /snap/gtk-common-themes/1353
    /dev/loop2           154    154         0 100% /snap/chromium/958
    /dev/loop3            23     23         0 100% /snap/snapd/5306
    /dev/nvme0n1p3    896193 285690    564911  34% /home
    /dev/sda1         468427    264    444301   1% /boot
    /dev/sdb1         112515  18036     88742  17% /1904
    /dev/sdd1         938772 397639    493440  45% /bak
    tmpfs                782      1       782   1% /run/user/1000
    mp3fs             896193 285690    564911  34% /tmp/music.mp3
    /dev/loop4            55     55         0 100% /snap/core18/1279
    /dev/loop5            23     23         0 100% /snap/snapd/5643

So, obviously, chromium accounts for /snap/chromium/958 and the snap
daemon accounts for /snap/snapd/5306 (but why is there also
/snap/snapd/5643?).

However what's using those other /snap filesystems, two of them with
core18 in the name and /snap/gtk-common-themes/1353?  Is there any way
of finding out, from the filesystem name, what package/software is
creating them?

-- 
Chris Green