It is essentially a painted rock, like my sister mentioned in her comment.
Be looking for this tutorial tomorrow. This picture was ultra simple, It was actually a sticky note taped to the back of the rock so I could see how it works.
When I do a craft that I haven't tried before I often search around for other crafters that have done it so I can learn from what they did. Because I have never done a craft for the first time and thought, "WOW, that was perfect and I wouldn't change a thing!"
So come back tomorrow for a DIY Saturday!