<http://schema.org/thumbnailUrl>
<https://drscdn.500px.org/photo/13893349/w%3D160_h%3D160_s%3D1/4b64f4030821dd76942d451785a4d245>
<https://marketplace.500px.com/photos/13893349/before-a-thunder-storm-by-sergey-suhanov>