圧し石[oshiishi] stone weight
一石[isseki] one game (of go)
一石二鳥[issekinichou] killing two birds with one stone
英国石油[eikokusekiyu] British Petroleum
下石[shitaishi] nether millstone

化粧石鹸[keshousekken] toilet soap
化石[kaseki] fossil
化石学[kasekigaku] paleontology
化石層[kasekisou] fossil bed
化石燃料[kasekinenryou] fossil fuel

月と鼈[tsukitosuppon] like chalk and cheese (superficially similar, but completely different) (the moon and a turtle shell are both round, but they are otherwise completely different)
鼈甲[bekkou] tortoiseshell (of the hawksbill turtle)
鼈甲色[bekkouiro] amber (colour, color)
石鼈[hizaragai] chiton (any marine mollusk of the class Polyplacophora)
鼈甲蜂[bekkoubachi] spider wasp

田鼈[tagame] Lethocerus deyrollei (species of giant water bug)
鼈茸[suppontake] common stinkhorn (Phallus impudicus)
鼈甲細工[bekkouzaiku] article of tortoise shell
鼈甲飴[bekkouame] hard candy