You've seen The Dress, The Bag, The Shoe and The Tracksuit - and now there's a new visual conundrum confusing the internet.

An optical illusion from two years ago has resurfaced on Twitter, and is still confusing people.

Some people see a rabbit being stroked, complete with long white-tipped bunny ears, while others see a raven.

In fact, it actually is a raven and scientist Dan Quintana has an interesting explanation for the human/rabbit illusion, which dates back to the early 1980s.

He said that by mentioning the 'rabbit's nose, he subtly directs people away from the (glaringly obvious) beak - basically planting the notion in their head that this is, in fact, a rabbit.

Most people had a sense of humour about it, at least.