Photographic paper is light sensitive. So any object placed on it and then exposed will leave a mark.
Photo-grams are the earliest form of photography and a fun technique to use. I used paper that has pre-printed postcard details on the back. ‘Silverprint” in London is a great shop for stuff like this and also bargain paper.
Unfortunately digital is killing traditional photography. Nikon has stopped making manual cameras, minolta is out of business
It is tragic. I thought you might like to know.