time capsule
noun [ C ] uk/ˈtaɪm ˌkæp.sjuːl/ us/ˈtaɪm ˌkæp.səl/
时间胶囊；时代文物密藏器（装入具有时代特征的对象后埋入地下，以供后世发掘研究）
a container that is filled with objects considered to be typical of the present period in history and then buried, so that it can be dug up and studied much later