Goblin sharks are deep-sea fish whose fearsome, protruding jaws were the inspiration for the terrifying creatures in the “Alien” movie franchise. Little is known about these elusive sharks, and sightings of them are extremely rare. They are known to live in deep coastal waters around the world but are not found in the Mediterranean Sea.

Recently, however, a group of scientists reported the discovery of what they said was a goblin shark that had washed ashore on a Greek beach. Their announcement of the discovery last year in Journal of Mediterranean Marine Sciences It led to a series of events as bizarre as the goblin shark itself, including competing science accounts, backsliding and the possibility that all the controversy was about a children’s plastic toy.

According to the original scientific paper, a Mediterranean shark was discovered by a man named Giannis Papadakis in August 2020. After finding the specimen, the paper said, Mr. Papadakis propped it up on some rocks and took a picture. The image ended up in the hands of a group of local scientists, and two years later they published it along with records of other species found in the Mediterranean for the first time.

The paper seemed like a success for citizen science, in which people with no formal science training help professional scientists with research. But it wasn’t long before shark experts around the world began expressing their skepticism, at A.J Facebook groupAbout the authenticity of the Goblin Shark.

“It wasn’t very good,” said David Ebert, author of Sharks of the World.” Dr. Ebert said that many things about the shark found in Greece were unusual. “They’re so small, their nostrils don’t look like they’re really open,” he said. “It doesn’t look normal at all.”

Dr. Ebert and others were also skeptical because there was no direct examination of the shark. The paper was based solely on a photograph and brief description provided by Mr. Papadakis.

In November, a group of shark researchers published a comment paper questioning whether the goblin shark found in Greece was a real animal. “We have suspicions,” they wrote, “that the goblin shark in the original paper is a “natural specimen.” They argued that the specimen’s lack of teeth, excessively rounded fins, and low number of gill slits were not characteristic of the goblin shark.

Soon after, another photo was shared on social media, which should cause suspicions to mount. It was a plastic goblin shark sold by an Italian toy company, DeAgostini, and it bore an uncanny resemblance to a goblin shark found in Greece.

Playmaker DeAgostini could not be reached for comment.

This game “shows great resemblance to the specimen in the published photo,” said Jürgen Pollersbock, an independent shark researcher and author of the paper that laid out the doubts about the Greek goblin shark’s authenticity.

Earlier this month, the authors of the original paper doubled down, standing by their original claims in response to concerns raised by Mr. Pollersbock and his colleagues. They also revised their size estimate from about 30 inches to about seven inches and suggested that the goblin shark in question could be an embryo.

“Embryos of this size are not viable,” replied Mr. Pollersbock.

Then this week, the authors of the original paper to retreat In addition to their response to the criticism, acknowledging that there is a great deal of uncertainty about the discovery. Via email, one of the paper’s authors declined to answer additional questions.

Thus ended the nearly year-long saga in which many shark investigators stared at their computer screens.

Mr Pollersbock said it was possible that goblin sharks were lurking in the depths of the Mediterranean. But he said none were found.

Whether the shark in this photo was found to be a real fish or just a piece of plastic pollution, critics say the publication of the photo in a science journal draws attention to the flaws in the scientific peer-review process.

“In my opinion, the problem and the responsibility lie with the journal editor and reviewers,” said Mr. Poulsbock.

He said the shark’s unusual appearance wasn’t the only red paper reviewers had to see. The claim in the paper was based on a single photograph provided by a citizen scientist, which warrants further scrutiny.

The editor of Mediterranean Marine Science did not respond to a request for comment.

Whether or not the researchers who published the now-retracted Greek shark paper admit to having published an image of the game, Dr. Ebert said he wouldn’t be surprised if something like this happened again, given the problems with peer review and rates of plastic pollution in the seas.

He noted that “anything is possible.”