memento
n
(pl ~s or ~es) thing given, bought, etc and kept as a reminder (of a person, a place or an event) 纪念品
a little gift as a memento of a visit 作为访问纪念的小礼品.
It has been estimated that the weight of all the insects destroyed by spiders in Britain in one year would be greater than the total weight of all the human beings in the country.