Two new pyramid complexes may have been discovered in a satellite survey of Egypt.
The potentially important sites, standing 90 miles apart, are made up of unusual-shaped mounds, according to archaeology researcher Angela Micol .
Ms Micol has spent the past 10 years searching for ancient sites from space using Google Earth.
The first area stands in Upper Egypt, some 12 miles from the city of Abu Sidhum along the Nile.
It includes a 620ft-wide triangular plateau - almost three times the size of the Great Pyramid.
"Upon closer examination of the formation, this mound appears to have a very flat top and a curiously symmetrical triangular shape that has been heavily eroded with time," she said.
There are also four mounds nearby - two around 250ft wide, and two 100ft wide.
The second site is 90 miles north, near the Faiyum Oasis, and 1.5 miles south east of the ancient town of Dimai, and contains a four-sided shape about 140ft wide.
"It has a distinct square centre, which is very unusual for a mound of this size and it almost seems pyramidal when seen from above," said Ms Micol, from Maiden, North Carolina.
The site also contains three smaller mounds "similar to the diagonal alignment of the Giza Plateau pyramids," she added.
"The colour of the mounds is dark and similar to the material composition of Dimai's walls which are made of mudbrick and stone."
Archaeologists are examining the images and will visit the sites to explore further.
"The images speak for themselves. It's very obvious what the sites may contain, but field research is needed to verify they are, in fact, pyramids," added Ms Micol, who has also found a possible underwater city off the Yucatan peninsula in Mexico.
In May last year, 17 lost pyramids were identified in a satellite survey of the country by US Egyptologist Dr Sarah Parcak of the University of Alabama.
Ancient Egyptians made buildings out of mud brick, which is much denser than surrounding soil, outlining the shapes of houses, temples and tombs.