Move over Howard Carter, there's a new mystery in town.
A team of architects and scientists have discovered "thermal anomalies" in the all three of the pyramids of Giza, found during an infrared thermography study as part of the search for hidden chambers within the pyramids.
In particular, three adjacent stones at the bottom of the Great Pyramid - also known as the Pyramid of Khufu or the Pyramid of Cheops, as it is the tomb of the pharaoh Khufu (Cheops) - have displayed "particularly impressive" anomalies in the form of higher than expected temperatures at ground level on its eastern side.
An international team, comprising experts from Egypt, France, Canada and Japan, have studied the pyramids during sunrise, as the sun heats up the limestone, as well as sunset, when they cool down. A statement from the Egyptian antiquities ministry said that they had "concluded the existence of several thermal anomalies that were observed on all monuments during the heating-up or the cooling-down phases".
There are currently "a lot of hypotheses and possibilities", including the presence of voids (empty areas) behind the surface, or internal air currents. We're going with reanimated mummies and/or ghosts though. That's what we think.
The three Great Pyramids are the tombs of the Pharaohs Khufu (Kheops), Khafre (Khephren) and Menkaure (Mycerinus) and were built in the Fourth Dynasty, between 2613 and 2494BC - they are the only one of the ancient Seven Wonders of the World still standing.
Experts will investigate further as the Operation Scan Pyramids project, which began on 25 October and continues through to the end of 2016.