Mystery of ‘Headless Pyramid’ solved

This looked worth of posting because it seems to fill a missing gap in the history of Egypt.

Archaeologists have uncovered the “missing pyramid” of a pharaoh and a ceremonial procession road where high priests carried mummified remains of sacred bulls, Egypt’s antiquities chief said Thursday.

Zahi Hawass said the pyramid — of which only the base remains — is believed to be that of King Menkauhor, an obscure pharaoh who ruled for only eight years more than 4,000 years ago.
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What's really interesting about the headless pyramid is that they found a burial chamber, even though the pyramid was (maybe) unfinished.

Only the pyramid’s base — or the superstructure, as archaeologists call it — was found after a 25-foot-high (7.6-meter-high) mound of sand was removed over the past year and a half by Hawass’ team.

The base was in a 15-foot-deep (4.6-meter-deep) pit dug out by workers, with heaps of huge rocks marking its entrance and walls. A burial chamber also was discovered.

same source

Archaeologists could learn a lot about how this particular pyramid was planned and constructed; and maybe add to speculation about the planning and construction of other pyramids, too.

I was hoping this discovery would be posted...Thanks!
I am no expert by any means but have tons of questions. Why is there only a base remaining? What made this one different from the rest?