"This morning skiing in Formigal with friends we've come across this," the man wrote. "What the hell is it? We've told the ski resort but they haven't taken us seriously."
"I bet there's something on the loose out there. I know what I saw."
The image managed to generate so much attention on social media that the ski resort ended up having to comb its slopes in an effort to reassure visitors that there wasn't anything there.
"We have spoken to the witnesses of the sighting to identify the area in which it took place and after combing the area we have found nothing," said a spokesman. "We believe therefore that there is no cause for alarm and that visitors' security is guaranteed."
The video footage - all three seconds of it - can be viewed below.