SEARSPORT, Maine — Mainers are justly proud of the state’s attributes such as succulent seafood, clean lakes, majestic mountains and the rock-bound coastline.

Now, residents can add something surprising to that list — a 19th century bottle filled with colored seabird guano that is on display until 2017 at the Smithsonian’s National Museum of American History in Washington, D.C. The bottle, with its intricate design, is a very rare artifact, according to Cipperly Good, the collections manager at the Penobscot Marine Museum in Searsport. It also helps to illustrate a little-known chapter of Maine’s shipbuilding and seafaring heritage.

“It’s part of our Age of Exploration,” she said. “We’re just proud that our collection has these hidden treasures that are of national significance. And it’s great that the nation can see it.”

During the 19th century, nitrogen-rich guano from bats and seabirds was a highly sought-after natural resource that came to be known as “white gold,” according to the National Geographic, because of its potency as a fertilizer. By 1850, guano cost as much as $76 per pound, or about a quarter of the price of actual gold, and its popularity meant that ships from as far away as Maine plied the waters of the Pacific Ocean in search of the dried bird droppings.

The world’s best quality guano was found in the Chincha Islands off the coast of Peru, where the dry climate allowed the piles of poop to grow to nearly 200 feet high. During the 1860s, the booming trade there led to a turf battle between Peru and Spain that is called the Chincha Islands War. America, which had a commercial interest in the region, installed a naval squadron to keep an eye on the region, according to the Military History Now website. The U.S. also ratified the Guano Islands Act in 1856 in order to claim guano islands in the Pacific Ocean and elsewhere.

“It was America’s first [expression] of imperialism, where we struck out and claimed foreign land,” said Paul Johnston, the curator of maritime history at the Smithsonian’s National Museum of American History.

The small mountains of guano on the Chincha Islands were excavated by Chinese laborers who likely were forced to be there, Good said. The conditions were hard, with the dust from all that nitrate causing workers’ eyes to bleed. Some of the Chinese workers reportedly jumped off the guano cliffs into the ocean to die in order to escape the forced labor, she said.

The museum’s guano bottle appears to commemorate a voyage by the Searsport-built ship Henrietta to Peru in 1880, toward the end of the guano boom. The resource was effectively depleted by the end of the 19th century.

“This is a very rare object,” Good said of the bottle. “We only know of three of them. It’s just so Victorian, to put sand in a bottle and make it into a design. But to make it out of guano is rare.”

The bottle might have been made by an American sailor who was waiting for his boat to be loaded with guano, or it might have been made by Chinese guano miners. According to Johnston, the Maine artifact is extra special because its ownership can be traced back to the captain of the Henrietta, right after the ship returned from a guano trip to the Chincha Islands.

“It has a totally clean, clear provenance,” the Smithsonian curator said.

The bottle was given to the Penobscot Marine Museum by the Carver family of Searsport and has long been a part of the museum’s collection of maritime artifacts. It stayed in Maine until earlier this year, when it made its voyage to the nation’s capital.

Curators at the Smithsonian had received a bound book of charts which included guano trade routes, and decided to mount a guano-themed exhibit. When Good learned the museum sought more guano objects for the Norie Marine Atlas & Guano Trade exhibit, which runs through January 2017, she thought immediately of the Searsport bottle.

“I said have I got the thing for you,” she recalled.

In Washington, D.C., the bottle joins other unusual treasures, such as a bottle of vintage homeopathic guano medicine that was advertised as a cure for both terrible headaches and itchy genitals.

“The fertilizer properties were so miraculous to farmers that unscrupulous snake oil salesmen made it into medicine,” Johnston said.

So far, the exhibit seems to be popular, especially among schoolchildren.

“The feedback is that they’re fascinated by this [bird] poop,” Good said. “Poop can be art.”

Johnston agreed.

“Everybody loves the subject of poop,” he said, jokingly. “But since we’re the Smithsonian, we call it aquatic avian excrement.”