[{
  "id": "PLACEHOLDER_SUBJECT_ID",
  "zooniverse_id": "PLACEHOLDER_SUBJECT_ZOONIVERSE_ID",
  "location": {"standard": "//placehold.it/640x480.png?text=Placeholder subject image"}
}]

[{
  "id": "PLACEHOLDER_SUBJECT_ID",
  "zooniverse_id": "PLACEHOLDER_SUBJECT_ZOONIVERSE_ID",
  "location": {"standard": "//lorempixel.com/640/480/animals/Placeholder subject image/"}
}]

Use a nicer placeholder subject image
Use a nicer placeholder subject image