It started out as an unspectacular find: a fragment of a whale skull, probably a few decades old, that was initially mistaken for a rock on a Brewster beach last September.

But recently, researchers realized they have something much more significant: a whale skull dating back at least three centuries that may provide a missing link between whales of yore and the present-day marine mammals.

On Sunday, the skull will be taken to its new home at the Smithsonian Institution in Washington.

Steve Haines for The Boston GlobE

Carbon dating tests conducted months ago determined that the skull was centuries old.

“It’s a great thing that somebody didn’t just say, ‘Let’s get a backhoe and get the damn thing out of here,’ ” said Charles W. Potter, marine mammal collection manager with the Smithsonian Institution, who came to Woods Hole to help prepare the specimen for transport. “It’s a valuable find.”

The skull was discovered poking out of the sand at Brewster’s Ocean Edge Resort & Golf Club. Hotel staff tried to dig it up, thinking it was a stone likely to trip a guest, but soon realized the object was bone.

Staff from the International Fund for Animal Welfare, an organization more accustomed to rescuing live marine mammals, excavated the bone and brought it to the Woods Hole Oceanographic Institution. For months, the skull piece, which weighs 300 to 400 pounds, sat in the lobby of the institution’s Marine Research Facility, labeled with a sign, “Please do not touch.”

Because researchers could not match the skull with records of whale beachings dating back to the mid-1970s, they initally estimated it was at least 37 years old.

But carbon dating tests conducted several months ago determined that the skull was centuries old, and further tests this week narrowed that window to sometime between 1630 and 1700, according to Ann McNichol of the Oceanographic Institution — a rare find that could provide scientists with important information about whale populations and marine ecosystems during the first decades of European settlement in New England.

“We didn’t have a clue it was so old,” said Michael J. Moore, a senior research specialist at the Oceanographic Institution. “It was a real sensation of gratification.”

Potter explained that whale skeletons found on beaches are either less than 100 years old, not yet having fully disintegrated, or more than 1,000 years old and turned to fossil.

A preserved whale bone dating from a few centuries ago is unusual, he said, and could provide information on whales from that missing link in time.

“It looks pretty scrappy — more like a piece of abstract art,” Potter said. “But there’s a tremendous amount of information in that skull.”

The bone likely comes from a North Atlantic right whale, though tests at the Smithsonian Institution are needed to confirm that.

Samples from the whale could be used to answer a host of questions: How well do right whales see and smell? How have their diets changed since the 1600s? What was the marine ecosystem like during that time period?

They may also be able to discern how the whale died, Moore said. It may have beached, dying of natural causes. Or, it could have been hunted by early settlers or Native Americans, Moore said — a possibility that could provide new insight into life on Cape Cod at the time.

“There are many stories that can be told from this one specimen,” Potter said.

After learning the skull’s age, officials from the Ocean Edge Resort & Golf Club and the Brewster Conservation Commission agreed that it belonged in the Smithsonian Institution, alongside the museum’s collection of more than 12,000 marine mammal specimens.

The chance that the 300-year-old whale bone could stay preserved out in the open on a beach was remote, Potter said. After landing, the bone was likely covered immediately with large amounts of sand, probably during a significant storm, preventing it from rotting.

“It’s sort of been in a little cocoon for the past 300 to 400 years,” Potter said.

And how do you transport it? Very carefully, as it turns out.

The bone — about 6½ feet long, 3 feet wide, and 2½ feet thick — sat on a foam pad, on top of a wooden pallet until Friday when researchers wheeled it into a marine mammal dissection laboratory and vacuumed up the dust (a mix of sand and disintegrated whale bone not viable for scientific testing, Potter said).

After that, the preparation process was somewhat akin to wrapping a fragile birthday gift: shrink wrap. Foam on all sides. More shrink wrap.

In the end, it looked like a fossil calzone, or, said Potter, “one of those extraterrestrial eggs out of a science fiction movie.”