Thanks for the clarification. They look like fossilised Great White Shark teeth, however , they have too much dentine around them. Shark teeth have supporting Dentine that extends upwards as a continuation of the tooth shape. (not enough to make a rectangle).
I was lucky enough to be offered a Lion Molar,(inverted "V") many years ago to mount in Sterling Silver. Very impressive chunk of enamel and dentine. Huge supporting structure. Easy when seen to understand how they can crush BIG bones.