a cactus spine is a kind of sharp object
another_sharp_thing is cactus. frailea is cactus. pseudorhipsalis is cactus. pseudorhipsalis is not cactus. frailea is not cactus. button_cactus is cactus. button_cactus is not cactus. lava_cactus is cactus. another_sharp_thing is not cactus. toothpick_cactus is not cactus.