The internet is once again stumped with a mind-bending photo: just how many girls does it show?
Photographer Tiziana Vergari from Switzerland uploaded the image on Instagram a week ago and it's since gone viral.
"It looks like there's 13 people," one commenter wrote.
"I think I stared at this pic for 5 minutes," another wrote.
Vergari's photo, featured also on @Instagram's feed, is just another one of the many puzzling photos that people just can't seem to figure out.
Remember trying to figure out whether the dress was really blue and black, or white and gold?
Or searching for the hidden panda in the sea of snowmen?