A stasis box was a technological artifact of the Slaver Empire, within which no time seemed to pass. (TAS: "The Slaver Weapon")
In the 2280s, a USS Tereshkova boarding party discovered documents aboard an abandoned Romulan science station that asserted that the Romulan cloaking device was actually based on a device found in a stasis box. (Star Trek: Shadowstar Station: "Hegemony")