To me the "lightbulb" is obviously a sail, because it's sitting on a well-known depiction of a boat. I think the snakes and some of the other hieroglyphs depict

To me the "lightbulb" is obviously a sail, because it's sitting on a well-known depiction of a boat. I think the snakes and some of the other hieroglyphs depict water passage. What I meant by ancient invisible technology is more like... consider a USB stick. What about that physical object would reveal what it is if you strip all cultural context (including language) away? When we see depictions of some ancient symbols (e.g. those handbags and wristwatches all over the ancient Middle East and Africa) I sometimes wonder if it is simply an unknown technological device - we'll never figure it out being in our time and place. Historians think everything is a temple or a tomb, instead of more everyday things like drive-thru restaurants and gaming devices. Surely those existed too, and if they did they probably iterated on them - they probably had some innovations we haven't thought of and wouldn't recognize today.