According to the man who photographed it and triggered a tidal wave of online curiosity: none of the above.

Robert Tyndall’s photo of a mysterious creature he found near the Swansea boat ramp confused and slightly unnerved locals when it washed up on social media on Monday.

Ethan Tippa, who shared it on Facebook, typified the general response.

“What the f--- is it?”

The answer, experts soon confirmed, was that it was a pike eel.

What was far from obvious from the photo, and what a bemused Mr Tyndall later revealed, was that the eel measured “about 1.4 metres”.

“I knew it was some kind of eel and it’s a big eel, but it definitely looks bigger,” Mr Tyndall, who found the eel while fishing last weekend, said.

“I think everyone enjoys using their imagination. Judging by the comments, it was growing by the minute.”

Mr Tyndall, of Caves Beach, said he was amused by speculation his image was Photoshopped, because he doesn’t “know anything about computers”.

To many, the angle made the eel seem longer than the species’ average maximum of 1.8 metres.

The nocturnal pike eel is common but surprisingly little is known about it.

Marine biologist Julian Pepperell said the species is frequently caught by fishers at night who get “the fright of their lives” when they reel in a powerful, thrashing predator with a nasty bite.

“There are certainly people who are bitten by them in boats,” Dr Pepperell said.

“They have incredibly strong muscle and their teeth are geared towards inflicting slashing wounds.”

An old fishers’ adage goes that a tinnie has room for a fisherman or a pike eel, but not both.

The photo of the long, sharp-toothed and clearly dead creature has been shared thousands of times on social media, with many identifying it as the similar but flatter-bodied largehead hairtail.

The eel at Swansea was probably “relatively old”, Dr Pepperell said, and could have died from a net entanglement, been hit by a boat or died of old age.

A Department of Primary Industries spokesman also said it appeared to be a mature specimen.

“Judging by the size it is believed that the eel was mature and may have died from natural causes,” the spokesman said.

Pike eels are not poisonous to eat, and are frequently sold in the markets of Southeast Asia.

They have been known to hunt 100 metres beneath the ocean’s surface for fish and crustaceans, and are more common off NSW than anywhere else in Australia.