Is this a photograph of the iceberg that did the unthinkable: sinking the RMS Titanic?

On April 12, 1912, Captain W. F. Wood aboard the steamer S. S. Etonian photographed a massive iceberg with a distinctive elliptical shape. Wood found the picture remarkable enough to print it out and annotate it with the current latitude and longitude.

Two days later, on April 14, the “unsinkable” Titanic struck an iceberg and sank to bottom of the Atlantic Ocean. That iceberg had the same elliptical shape, according to sketches made on the ship. Wood had captured the remarkable piece of ice, said Craig Sophin, a Titanic expert and consultant to the auctioneers.

“There were probably thousands in the North Atlantic at that time -- but few that looked like this iceberg,” Sophin told FoxNews.com. “This was such a huge monster, with such an unusual shape … it’s like a snowflake, no two are exactly alike.”

'In my professional judgment, this iceberg is the one that sunk the Titanic.' — Titanic artifact collector Stanley Lehrer

“It was very reasonable to conclude that this iceberg … probably was the very same iceberg that Titanic encountered 10 days later, 2 miles south,” he said.

An iceberg expert contacted by FoxNews.com was unwilling to say definitively one way or the other.

“The berg shown is probably around 25 meters [82 feet] high, 80 meters [262 feet] wide based on the waves and general look -- this is a typical highly deteriorated iceberg around these parts,” said Dr. Steve Bruneau, a professor of iceberg dynamics at Memorial University in Newfoundland and the author of “Icebergs of Newfoundland and Labrador.”

“Bergs of this size are hundreds of thousands of tons -- perfectly sufficient to afflict fatal damage to any ship. So plausible? Yes. Certain? Not really,” he told FoxNews.com.

But Sophin and other Titanic authorities are convinced.

“In my professional judgment, this iceberg is the one that sunk the Titanic,” Titanic artifact collector Stanley Lehrer said. Sophin cites as additional proof the coordinates captain Wood wrote on the face of the photograph.

“When you put those coordinates on the graph, and look at Titanic’s foundering position, it appears he saw this iceberg approximately 10 miles northeast of Titanic. The current was moving south at that time, meaning this iceberg was drifting towards Titanic’s position,” he said.

Icebergs can vary greatly in mass, particularly the hidden bulk submerged beneath the waters. Bruneau pegs this one at around half a million tons, or 1 million pounds -- fairly average, he said, though some reaching several million tons are common as well. Their pace can vary widely too, Bruneau said.

“Bergs typically move around 20 kilometers [12.4 miles] a day when drifting freely off the coast of Newfoundland, but the rate can be four or five times this,” he told FoxNews.com.

That speed would have moved this iceberg far from the Titanic within two days -- further evidence that this photo, while remarkable, may be simply an artifact of a different age.

It’s also one of many photographs that have been labeled “the big one.” Indeed, Sophin himself admits to having several in his collection. He firmly believes Captain Wood has captured the right one.

“When I looked at the drawings made almost in real time by people who saw the iceberg, …. I relented to the fact that I no longer had the photo of the iceberg. It was here.”

Bobby Livingston, vice president at RR Auctions which will sell the photograph on the 16th, also sticks to his guns. This photo is the real deal. But regardless of whether it’s the iceberg or just an iceberg, enthusiasm for the photo -- which is expected to sell for $10,000 or more -- is running high.

“There’s an incredible interest in the Titanic story, because it resonates so greatly with us,” he told FoxNews.com.

“That kind of tragedy speaks to a lot of people and makes it one of those events that’s unforgettable in the human experience,” he said.