That stuff between the hippo’s teeth? Slow-moving pharaohs. ;’)
The other reasons Tut’s tomb wasn’t looted: robbers dug their way in during pharaonic times, probably within a few years (or even days, weeks, or months) after the burial, as Carter found the hole they wormed through, but they only got into the first chamber, and must have been discovered, or got caught with whatever items they managed to remove; also, a later pharaoh’s excavations used the area of Tut’s entrance as a dump site for the stuff removed by the new mining.