Since being posted, the image has attracted over 150 comments, with users debating the correct number of triangles. Answers ...

A shapeshifting lampshade fools your brain into seeing something that isn't there with the clever placement of light. The light fittings look like 3D cubes from the distance but are actually ...

READ ALSO: Optical illusion: Only those with sharp vision can spot all three bananas in 5 seconds Extra clue: there is at most one guard wearing a triangle mask on each row. Once you see one ...