Located at the University of Pennsylvania in Philadelphia, the Penn Museum has a fine collection of Egyptian artifacts, but the one above stands out as a real example of lost ancient high technology. It is made of a very pure and very hard basalt stone.
Both the grey/black sarcophagus and that above, made of granite, are believed to have been made during the Ptolemaic or Greek period of around 2000 years ago. But the difference in quality of finish is remarkable. The grey/black basalt work is as even and smooth as that done with modern machines, while the granite one is much rougher, with many depressions and pits.
The hieroglyphics, above, are cruder in execution than the sarcophagus itself, and were likely added later, as in during dynastic times. This is very similar to what we see in a box in the Serapeum of Saqqara, shown below. A magnificently made smooth hard stone box with crude symbols etched onto the surface.
Yousef Awyan, in the above photo is pointing out the rough execution of the symbols as compared with the smoothness of the surface. Clearly this box was made prior to dynastic times by an unknown civilization that had lost ancient high technology. The dynastic people found it and etched in the crude hieroglyphics later.
The lower section of the sarcophagus was added by, presumably, the museum. Look at the amazing bilateral symmetry of the work, and the transition from the sharp edge to the upper curvature. To presume that this was achieved with even hardened steel chisels, which the Ptolemaic people could have possessed is ridiculous.
Also, the curvature of the top of the shoulder is remarkably smooth, and the cut line, where the head and neck portion connects with the body appears original, and likely could only have been achieved with a power saw of some kind. Damage to the edges likely came later, when it was being moved from its original location.
Above is a video taken in early April 2017, showing the difference in the quality of work of the two sarcophagi.