First there was the “The Dress,” then the Yanny or Laurel debate — and now, the great “bird or bunny” battle of 2019.

Internet users have been going back and forth over the latest optical illusion craze, which got started by a Twitter video on Sunday.

Daniel Quintana, a senior researcher in biological psychiatry at the University of Oslo in Norway, posted a short clip on his page — showing an animal being rubbed on the head.

“Rabbits love getting stroked on their nose,” he tweeted, planting a small mental seed to show the power of suggestion.

“I thought it was fairly clear that the video was of a bird,” Quintana later told CNET in an email.

“As you can see the translucent nictitating membrane sweep across the eye horizontally (rabbits don’t have membranes like this) and the positioning of the ‘ears’ are a little strange,” he said. “I made the rabbit comment to prime readers into thinking it was actually a rabbit, to give it a fighting chance at least. When you only see the beak in your peripheral vision, it really seems like they’re ears. Without this misleading cue, I thought most people would have seen a bird.”

The idea was based off “the static bird/rabbit illusion” created by psychologist Joseph Jastrow in 1899 as a way to prove the power of suggestion, Quintana said. He reportedly used a video that had been posted by the photo service Imgur on Saturday.

“The static bird/rabbit illusion is well-known within psychology and philosophy, so when I saw [the Imgur] video, I thought it would interesting to share it, ” Quintana said.

As he expected, countless users pounced on the “rabbit” footage and began voicing their opinions on what type of creature it really was.

“That’s a feckin crow,” tweeted one person.

“Not sure if rubbing left looking rabbit on the nose or an upward looking bird on the head (ears=beal),” another said.

Quintana eventually revealed that the creature was, in fact, a bird — most likely a “white-necked raven” or Corvid. Several users were able to come up with the correct answer on their own.

“That is not a rabbit, it is indeed a Corvid,” wrote @GretaGarbolini. “Notice the nictitating membrane when it blinks. Instead of moving up and down, it sweeps across the eye horizontally like a windscreen wiper and is translucent.”

People were comparing the internet debate to “The Dress” and “Yanny or Laurel” discourse from 2015 and 2018, respectively.

For “The Dress” illusion, social media users were tasked with figuring out whether a dress was black and blue or white and gold. The “Yanny or Laurel” dispute stemmed from an audio clip in which a robotic voice repeats a single word over and over again, with users having to choose between Yanny or Laurel.