鈷 - cobalt

single-pronged vajra; tokko; dokko; copper or iron implement, pointed at both ends, used in esoteric Buddhist rituals

ground stone tool from the late Jomon period

ground stone tool from the late Jomon period (named after its similarity to the Buddhist tokko)

three-pronged vajra flung by Kukai on his return from China to determine the Holy Land of Esoteric Buddhism

trident vajra