Eating your subject

Moments after taking this photograph of lemon cake with lemon sauce, I devoured the subject matter. Now there's only the photo that this piece of cake ever existed.

Does the disappearance of the subject change the significance of the photograph?

I occasionally look at a painting by the late Geoffrey Rock, which was purchased when he was alive, and have strange feelings about this thing that he created that outlived him. Is he a part of it?

Am I a part of this photo? Part of the photo is certainly part of me.