After discovering King Tutankhamen’s tomb, the British archaeologist Howard Carter spent years cataloging the thousands of priceless artifacts inside, including life-size statues of the ancient Egyptian pharaoh, glittering thrones, and the boy king’s funeral mask.

He also pilfered some for himself.

Now, one object that Egyptologists have for decades said that Carter likely stole is to be auctioned — despite some experts saying the sale should not occur.

On Sunday, Apollo Art Auctions, a small auction house in London, is to sell the so-called Guennol Grasshopper. The intricately carved ivory and wood container is in the shape of the noisy insect, with wings that swing outward to reveal a hole to store perfume.

The grasshopper, which the auction house says in promotional material is “from the age of Tutankhamen,” has an estimated price of up to 500,000 pounds, or about $675,000. The auction listing says the item previously traded hands for $1.2 million.

Apollo Art Auctions said in an emailed statement that there was “no documented evidence” that the vessel came from the pharoah’s tomb. “The item does not appear on any official excavation inventories,” the statement said.

Still, for some Egyptologists there is little doubt about its origins. Christian Loeben, of the Museum August Kestner in Hanover, Germany, who has written about Carter’s career, said in an interview that he was “quite convinced” that the grasshopper could only have come from the tomb.

The artifact is of a style that existed in Egypt at “exactly the period” of Tutankhamen’s reign in the 14th century B.C., Loeben said, while the vessel’s lack of damage indicates that it came from a sealed chamber like the boy king’s.

Historical records also show that Carter sold the item after returning to England.

Loeben said the grasshopper should go back to Egypt. “It’s a moral question,” he said.

Christina Riggs, a professor at Durham University in northern England who has written extensively on Tutankhamen and on Carter’s behavior, said that Carter took other small artifacts, including some designed to look like animals. Some, she said, are still in Western museum collections.

Riggs said it was unsurprising that there was no documentation of the grasshopper’s origins: Carter wouldn’t have listed items he stole as being among the tomb’s contents.

She said the auction house should have consulted the Egyptian government. The Egyptian Ministry of Tourism and Antiquities did not respond to requests for comment for this article; nor did a spokesman for the Egyptian government.

Apollo Art Auctions said it was “confident that the sale complies fully with all applicable laws and international standards, and we have taken all necessary legal and ethical steps to ensure the legitimacy of the object’s provenance.”

The auction house also said that the Art Loss Register, a London-based company that maintains a database of stolen artifacts, had issued a “certificate of clearance” confirming that the item was not listed.

James Ratcliffe, the register’s general counsel and director of recoveries, said in an interview that the item sat in “an awkward area”: There are questions about its origins, but the Egyptian government has never reported it stolen or asked for its return.

When Carter and his patron, the Earl of Carnarvon, began searching for Tutankhamen’s tomb in 1914, they hoped for a big payday. At the time, the Egyptian government let archaeologists keep half of any discoveries if robbers had already broken into a tomb. Carter argued that this was the case for Tutankhamen’s chamber, although many have disagreed with his assessment.

In any case, the Egyptian government decided to keep everything.

In December 1922, shortly after Carter unveiled the tomb to the world, an article in The New York Times said that the British archaeologist’s “unceasing work” would “go unrewarded,” as the government decided to “regard the tomb as royal and untouched by robbers.”

Shortly after Carter’s death in 1939, his niece discovered items among his belongings that were inscribed with Tutankhamen’s name, and some were returned to Egypt. In 2010, the Metropolitan Museum of Art in New York returned 19 items that it said could be “attributed with certainty” to his tomb.

Today, on the outskirts of Cairo, more than 5,000 artifacts from the boy king’s tomb are intended to be the biggest draw in a new Grand Egyptian Museum — although for now the Tutankhamen galleries are closed. Tutankhamen’s gold funeral mask is displayed at the old Egyptian Museum in the city.

Although the Egyptian government hasn’t claimed the grasshopper, which has long been held in private collections, experts have for decades linked it to the tomb. In 1978, Thomas Hoving, a former director of the Metropolitan Museum of Art, published “Tutankhamun: The Untold Story” in which he said the grasshopper, “so deftly fashioned that the insect seems about to take flight,” had “always been linked to the Tutankhamen treasures.”

Erin Thompson, a professor of art crime at John Jay College of Criminal Justice at the City University of New York, said in an interview that the she wasn’t surprised that the sale was occurring at a lesser-known auction house. Major auction houses like Christie’s and Sotheby’s, she said, “wouldn’t touch an antiquity connected so closely to a known pilferer.”

For Thompson, the auction raises wider questions about the ethics of selling potentially looted artifacts. “Should we return only the handful of artifacts whose histories we can trace step by step?” she asked, adding, “I think we should make repatriation decisions by thinking about what’s right, not just what’s provable.”

Rania Khaled and Vivian Yee contributed reporting from Cairo.