.prj files

I was recently sent sessions there were originated in Cubase (I believe version 3) that have .prj file extensions as instead of .cpr extentions. Is there a wasy to convert these to .cpr files or is there another way to open these projects with either cubase or nuendo. Any help would be appreciated. BTW I am on Nuendo 5.5.



Cubase never had .prj file extensions.