The 'lightbulb' at Dendera — I've stood in that crypt, let me explain

Everyone's seen the meme. The Dendera 'lightbulb' relief. Temple of Hathor, and you have to go down into one of the southern crypts, narrow as a coffin, to see it. Three carvings. A big bulb shape, a lotus flower at the base acting like a socket, a wavy snake inside like a filament, and a thing unde……