Dear Felix,
They are the Project files. The FCP icon for a project that is. No idea why it has happened but I will check for this vault file when I go in today.
All the project files have been corrupted that were on this disk (ie for other projects too) but they were not open when I unhooked the external drive from the machine so I dont know why this has happened.
Thanks for all your help!
Best, Tina