An hourglass in Riann's shop
An hourglass was a time measuring equipment consisting of two connected glass containers through which sand flowed when upended.
The Akaali apothecary Riaan kept an hourglass in her apothecary shop on the Akaali homeworld in 2151. (ENT: "Civilization")
Gabrielle Burnham described the usual perception of time as being "fragile. Precious. Beautiful. Sand in an hourglass, all that." (DIS: "Perpetual Infinity")