Loop Device mounts are never cleared when the volume is unmounted.  You have to close dolphin and open it again for it to go away.  If you do this frequently, they can really build up.  It's especially confusing if you're working with more than one loop device.

Reproducible: Always

Steps to Reproduce:
1. Open Dolphin
2. Open Konsole, or a Konsole view in Dolphin
3. Run these commands (enter your password for sudo):
truncate -s 100M mydrive
mkfs.ext4 -FL TestFS mydrive
mkdir mymnt
while sleep 1 ; do
 sudo mount mydrive mymnt
 sleep 1
 sudo umount mymnt
done
Actual Results:  
Icon for "Loop Device" shows up in Places when ''mydrive" is mounted, but it doesn't go away when it is dismounted.  When you mount it again, a new entry is created.

Expected Results:  
The Loop Device entry should be cleared away when "mydrive" is unmounted.

Additionally, the label "Loop Device" isn't particularly helpful - it ought, rather, to use the volume label ("TestFS" in the example above.)