<http://schema.org/thumbnailUrl>
<https://drscdn.500px.org/photo/21233087/w%3D160_h%3D160_s%3D1/c2a49a29e01d8e2ab955c2138f3c7f34>
<https://marketplace.500px.com/photos/21233087/descent-by-steven-wosina>