Are you trying to these files into a specific program, or just looking to extract them?
When you open a "7z Extra" archive, you will generally find the following components: santa_extra.7z
Because the file itself is a .7z archive, you need a compatible decompression tool to "look into" it: Are you trying to these files into a
: Install the p7zip-full package via your terminal to manage .7z files. santa_extra.7z