I think fox too – our front garden has been consistently decorated in them and the cats are not too keen on going out that way at night! The back garden is all fenced in so they are happy that way (and no fox poo).
I figured it probably was as there is a lot of calcium in it (bones etc). My dog used to love rolling in the stuff, made him smell alluring (he seemed to think) but now he is so old and arthritic he doesn’t seem overly interested!
Quite why the fox has his or her nightly movement by my front door I don’t know! I keep thinking of getting a night cam to catch them in the act – Wildlife Photographer of the Year here I come… with a crapping fox picture!