(CNN)A mystery SOS sign in a remote part of Australia has confused police after a search found no evidence of “recent human activity” in the area.
The large sign, made of rocks, was spotted recently by a pilot flying over Swift Bay in Kimberley, Western Australia’s northernmost region. A police ground search followed.
The emergency signal raised concerns that people may be missing or stranded, but after an inconclusive investigation, authorities are now appealing to the public for information.
It’s also possible that the distress sign was created months ago and went unseen, or that the sign is simply a prank.