The other side showed that part of this piece must has been a tissue box, according to the fresh clean tissues:
Even without seeing the name of the sender, I immediately knew this must have been Dean's hand who turned a tissue box into Mail Art.
And my knowledge was proofed right when I pulled out the tissues (which were handy because I had spilled some coffee). It's Dean's 1326th piece of Mail Art:
I felt very brave when I took out the tissues!
Usually I am not able to change received mail art, because I think it destroys the original work of art. Some other mail artists dare to do so, but for me this is the very first time.
Even though Dean encouraged me to do so, I still left his other tissue box mail art complete. Already for almost two years. This is the piece of Mail Art I mean, Dean's 869th piece of mail art, received September 2014:
So I still don't know what has been hidden besides the fish and chips, behind this tearable closed opening...
Thank you very much, Dean!