From King Dictionary of Contemporary English
Related topics: Utensils
egg-timerˈegg-ˌtimer noun [countable] DFUa small glass container with sand in it that runs from one part to the other in about three or five minutes, used for measuring the time it takes to boil an egg
Examples from the Corpus
egg-timerJoyce's family is numbered with the grains of sand in a thousand egg-timers.