<http://schema.org/thumbnailUrl>
<https://drscdn.500px.org/photo/18618097/w%3D160_h%3D160_s%3D1/807214d5a6a8cb6274af28ad26c15df1>
<https://marketplace.500px.com/photos/18618097/a-silhouette-by-venkatesh-alok>