The backroom storage areas of a museum are rarely visited by the public. But these facilities contain the research collections—the wellspring of what is presented in the galleries and exhibits. Museums all over the world have extensive collections hiding behind the scenes, cluttering back rooms and filling storage units. Skeletons, paintings and trinkets all housed and inventoried, often wait to be examined, studied—or rediscovered.

Researchers at the Smithsonian’s National Museum of Natural History in Washington, D.C. today announced that a rediscovery in the collections has been made. A 300-pound sperm whale fossil that had been misinterpreted as an extinct walrus almost a century ago is newly renamed Albicetus oxymycterus, based on the Latin for white whale (albus cetus), after Herman Melville’s classic novel Moby-Dick, the subject of the new Ron Howard film In the Heart of the Sea.

The finding, which was published today in the journal PLOS ONE, will teach scientists more about the evolution of whales in our oceans, says co-author Nicholas Pyenson.

"Not everything in a museum is known," says Pyenson, who is a paleontologist at the Natural History Museum. "I have access to the greatest collection of modern and fossil whale specimens."

The Moby-Dick fossil was first described back in 1925 by Remington Kellogg, who was working as a biologist at the Carnegie Institute. (He would later become in 1958 an assistant Secretary at the Smithsonian.) The fossil skull, which weighs several hundred pounds, originally came from California. Kellogg saw that the skull had a big tooth and assumed the animal was a walrus. For decades, that classification stood—until Pyenson decided to investigate.

"Ten years ago when I was a student, I made a trip to the Smithsonian, and there was this big skull, and it was well worth further study because the last time anyone had published on it in was 1925," says Pyenson, who worked with the Smithsonian’s Digitization Program to have the whale skull, which could be up to 15 million years old, scanned and digitized. Today, that 3D scan is made available online to other scientists as well as the public.

This discovery can tell us a lot about the evolution of sperm whales throughout time, says Ari Friedlaender, a marine ecologist at Oregon State University. Scientists can compare the sperm whale fossil to other fossils, as well as today's modern sperm whales. The differences among the animals can help tell us about the world's oceans and climate in the past.

"[This study] is a great example of how you can use the past to understand the present and how the fossil record provides us with information on how these animals evolved," Friedlaender adds.

Modern sperm whales are among the biggest animals in the world, growing up to 60 feet long. The Albicetus oxymycterus, however, is estimated to have only been about 19.6 feet. Why the difference in size? This is most likely due to an evolutionary arms race between the whale and its prey, says Alex Boersma, a researcher at the Smithsonian.

Sperm whales mainly eat giant squid, which can be vicious creatures. Squids have powerful suction cups and sharp, deadly beaks. "You'll find sperm whales who have suction cup marks and scratch marks from the squid beak," Boersma adds.

The sperm whales may have grown larger as the squids grew larger, each trying to best the other.

The redescribed fossil also has a row of upper teeth unlike the modern sperm whale, which only have teeth on their lower jaw. Today’s sperm whales swallow their food whole, and the one set of teeth is more for grabbing and ripping than for chewing.

But the sperm whales of yesteryear had two sets of teeth and a powerful lower jaw. This means that prehistoric whales were probably feeding on other marine animals like smaller whales and seals. They would have needed teeth for catching and eating their prey, Boersma says.

"That's something we don't really see in modern whales anymore, other than the killer whale," she adds. "This suggests there was some sort of shift in the evolution of sperm whales, and they changed their feeding strategy."

The next step is to do more research and find other whale fossils from different time periods. There's still a huge gap in the fossil record between the Albicetus oxymycterus and today's sperm whales.

"The science and methodology is so meticulously detailed that it would be difficult to argue with their conclusions," says Kathryn Davis, an environmental historian at San Jose State University. "This was probably the most impressive part of this paper. The description of methods, technology, and attention to the original description is, I think, beyond reproach."

This discovery is also a call to action for museum curators around the world. It's time to clean out those basements, open up those storage sheds and reexamine those back rooms. It's likely that there are many more misidentified fossils, and it's up to museums to dig deeper, Davis adds. "The science, the use of historical data and description, are all exciting but the possibilities are endless and that is what is really important about this article."

"This article should engender new excitement about re-examining determinations made in the 19th century because of the possibilities for new knowledge," Davis says in an email. "That might provide us with a new window on exploration of the past, evolution and extinction."

UPDATE 12/10/2015: A previous version of this story suggested that Remington Kellogg described the fossil as a walrus. In fact, Kellogg identified it originally as a whale and subsequent research redefined the genus as a group of extinct walruses. Kellogg was also described as a Smithsonian employee at the time, but he did not arrive at the Smithsonian until many years later.