If they were for applied decoration, would it not make more sense for them to be hollow or hammered out so as to use less metal?
Ave!
Yes, that would make more sense, but they were not.
1st photo is the back of vine leaf decoration - Copper
alloy; 48mm/56gm and big and that's heavy!
All that shiny stuff is the original
Roman solder.
Over the years I have
had 30 or more vine leaf wine vessel adornments (see 2nd photo for the various shapes) and only three that were shell-shaped like Vladimir's.
All of them
had solder on the
reverse for attaching to the vessel or
bowl.
The only way to determine if Vladimir's shell is an
AEs formatum or not is to clean off the
reverse and look for the presence of residual solder.
Just my two cents worth.
Kevin