Yes, there is, but I'm not sure I understand what you mean.

If you want to save all your open tabs as bookmarks, you go to the Bookmarks menu, choose "Bookmark all tabs" and Firefox will save them all in a folder with a name you choose. Then you can go to the Bookmarks menu, choose this folder, and when it opens you can either click any bookmark in it or choose the bottom option, "Open all in Tabs". 

Or did you mean something else?