Instead, the lack of artwork and inscriptions, as well as the structure's red granite blocks, were typical of Old Kingdom pyramids, according to Hawass.
The burial chamber also contained the lid of a sarcophagus made of gray schist, a type of rock often used in the Old Kingdom.
What's more, the newfound pyramid resembles the pyramid next to it, which belongs to the first pharaoh of the 6th dynasty, Teti, who ruled from 2345 to 2181 B.C. That suggested the lost pyramid could also come from the 5th dynasty.
The neighboring pyramid also pointed to the owner of the pyramid as Menkauhor, since he was without a discovered burial tomb.
"There were missing pyramids of the kings, and this is one of them," Hawass said.
Archaeologists also announced the discovery of new parts of a sacred road, dating to the Ptolemaic period, some 2,000 years after the Old Kingdom.
The discovery shows the sustained importance of Saqqara, which was located in the ancient capital of Memphis, the researchers added.
Ola El Aguizy is a professor of ancient Egyptian languages at Cairo University.
"During the whole history of Egypt, Memphis and Saqqara had remained very, very important," El Aguizy said.
"I am discovering tombs of people of the 26th dynasty [in Saqqara] that were reusing tombs of the 19th dynasty. It is a sacred place, and so many important people wanted to be buried there."
Another reason people wanted to be buried in Saqqara was the sacred road, which was used for the procession of mummified bulls of the god of the dead, Osiris.
"[Osiris] was enthroned like a king and when he died they made funerals like those of a king," El Aguizy said.
The bulls also had a historical significance: Their deaths were used to determine when a pharaoh reigned.
"It's a way of dating the pharaohs," El Aguizy said. "Sometimes we know how many bulls died during the reign of a king, or vice versa."
More Discoveries Expected
The sacred path, first discovered by French archaeologist Auguste Mariette in 1850, is nicknamed the Way of the Sphinxes because of its long row of statues often found at the gates of Egyptian temples.
(See a photo gallery of Egyptian landmarks.)
"The modern name of ancient Memphis is Mit Rahina which means the way of the Sphinx," El Aguizy said.
"So [this path is] presumably the Way, with sphinxes [formerly] on the two sides."
Archaeologists hope the path will lead to more discoveries in the area. Plans are underway to relocate modern-day workers who live in a village beside the Menkauhor site to allow an expanded search for more temples.
"When I say we've discovered 30 percent of the Egyptian monuments, I take Saqarra as the first example," Hawass said.
"Saqqara is a virgin site," he added. "It's very important for us to do this excavation to understand more about the pyramids of the Old Kingdom."
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