This prompt was about using a small aperture number on the camera. What this does is give a very narrow area of a subject that is in focus and blurs the rest of the image. In this photo I have focused around the hole in the skull which falls in the centre of the image. Because of the narrow depth of field the area in the foreground and then in the background are blurred, as is everything in the distance. The amount of blur is also dependent on how far away the camera is from the subject, as well as the distance from the subject to the background.
I found this skull many years ago - and when I stop to think how many years ago it was, I figure it's better not to know! I have no idea what type of animal this came from but I have carried it around with me and it sits on one of my display shelves - along with my bird's nest and snake skin.