scientific name: Trapa natans, and another species Trapa bicornis
the Chinese water chestnut that Americans are familiar with
scientific name: Eleocharis dulcis, among other species
People in the old days would say apulid tsina (Chinese chestnuts).
Because Filipinos refer to brown chestnuts as kastanyas, they sometimes force-translate "water chestnut" as tubig kastanyas, but this is not common.