<http://schema.org/thumbnailUrl>
<https://drscdn.500px.org/photo/18014867/w%3D160_h%3D160_s%3D1/255cc06aeb46e2ebf3f716fa8ca16bcc>
<https://marketplace.500px.com/photos/18014867/caught-in-the-act-by-saurabh-mishra>