Teams have been digging in the area for more than 20 years.
"One hundred years ago they used to take sand and put it in unexcavated areas," Hawass said.
"The archaeologists in the past used this area as a location for the sand. No one could think there is anything here."
Tomb robbers, however, had known the pyramid was there—archaeologists found that a shaft had been created to allow access to Sesheshet's funerary chamber.
Due to those assumed tomb raids, archaeologists don't expect to find Sesheshet's mummy when they reach the burial chamber weeks from now. But they do anticipate finding inscriptions about the queen, whose name, perhaps coincidentally, evokes the goddess of history and writing, Seshat.
Starting from the 4th dynasty (2616 to 2494 B.C.), pharaohs often built pyramids for their wives and mothers.
"Mothers were revered in ancient Egypt," said Salima Ikram, a professor of Egyptology at the American University in Cairo, who was not involved in the discovery.
"Building pyramids for one's mother in her dead state was fairly emphasized in the whole vision of kingship that the ancient Egyptians had," Ikram said.
"That was something that was instituted during [a pharaoh's] lifetime and was a very public way of expressing his debt to her, his connection to her, and her importance in Egypt politically and as a symbol for kingship."
Sesheshet's son Teti might have been more motivated than the average pharaoh to pay homage to his mother. Sesheshet had come from a powerful family and probably supported his ascendancy to the throne during turmoil at the end of the 5th dynasty.
"She's one of the important ladies at that time," said Hakim Haddad, general director of excavations in Egypt.
"At the end of the 5th dynasty and the beginning of the 6th dynasty, there was a conflict between two branches of the royal families."
The American University's Ikram added, "I assume Teti thought it would be a good plan to make his mother a pyramid."
Regardless of Teti's motivations, SCA director Hawass says the newfound pyramid is special because of its association with a female ruler.
"You can discover a tomb or a statue, but to discover a pyramid it makes you happy. And a pyramid of a queen—queens have magic."
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