It was the smell that lead him to it at Lake Cathie and prompted him to snap a few photos.

A variety of experts have been asked for their opinion but none seem to know what it could be.

Even when asked to hazard a guess the response is the same.

Dave Harasti, Marine Scientist (Marine Ecosystems Research) with Fisheries NSW, Department of Industry could only say:

“Sorry, but I have no idea.”

Brian Hughes, Estuary and Marine Officer with the Hunter Local Land Services also has no idea what it could be.

The man who took the photos sent them to the Museum of Sydney and they have not been able to enlighten him as to what it could be.

One likely scenario is that the storms and strong seas ‘unearthed’ the normally deep sea creature.

A similar mystery played out further south at Swansea when a “messed up crocodile” was photographed at the boat ramp there.

Reporting on the incident at the time the Newcastle Herald described the tidal wave of online curiosity that resulted from the photo.

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.

If you think you know what our Lake Cathie ‘mystery mouth’ is email janine.watson@fairfaxmedia.com.au