Can you spot all the hidden circles in this renowned optical illusion?

If you can spot the 16 circles here, you’re spot on.

A renowned optical illusion from the mid-2000’s is circulating around the internet once again, posing the challenge of finding each of the hidden round objects among several black-and-white rectangles and straight lines.

“Look closely. There are actually 16 circles in this image. And once you see them, the image appears changed forever.” Tweeted cognitive psychologist Dr. Gavin Buckingham.

The image itself — where the circles appear within the straight lines between the rectangles -— is known as a “Coffer” illusion, and it was created by San Francisco based vision scientist Anthony Norcia in 2006.

It was considered to be one of the top ten illusions from that year, according to Illusionsindex.org.

His busy image “belongs in a large class of illusions where a two-dimensional figure, or three-dimensional object can be seen in two or more sharply distinct ways,” the site reported.

Though, there is controversy over how people’s perception of the illusion changes once one sees the circles, per the index.

“What is not agreed is whether the visual experience of the figure changes when the perspectival switch takes place between seeing the circles versus not seeing them, or whether the experience itself does not change, and it is some post-experiential belief, judgment, or other mental process which changes,” the site reported.

“Ambiguous figures like the Coffer have been cited in debates about whether the nature of experience can be fully accounted for by appealing only to its representational content.