<http://schema.org/thumbnailUrl>
<https://drscdn.500px.org/photo/24250351/w%3D160_h%3D160_s%3D1/6c8b4911c94da1d85416d87d5fdc175a>
<https://marketplace.500px.com/photos/24250351/light-and-shadow-by-chihiro-imahashi>