Also known as: 砂時計, 沙漏
A timing device made with two bulbous pieces of glass connected together, where sand or similar material inside the glass can trickle through one bulb to the other to measure a certain amount of time, whether it is in minutes or an hour. When all of the material has passed through, the hourglass can be turned over to start the process again.
For an "hourglass" body shape, see Curvy.