Zhu Xi’s famous comment on “seashells on high mountain(高山有螺蜯殼)” used to be compared with the principle of fossilization in modern science and praised as an accomplishment of Chinese science. These comparisons and compliments has been criticized by many historians and now it is clear that looking for the similarity to modern concept of fossil is inappropriate to show the significance of Zhu Xi’s comment on seashells. Instead, the comment can be properly considered as an explanation to rationalize seashells on high mountain in Confucian cosmological principles. This paper examines how literati of Chŏsun understand Zhu Xi’s comment on seashells in 16th-18th century Korea. Why did they gave attention to Zhu Xi’s comment on seashells? How did they utilize the comment in their writings and for what purpose? Answering these questions, I will suggest that the understanding of Zhu Xi’s comment in Chŏsun was associated the discourse of “odd things” often doubted to be existed since ‘the past universe(先天地)’. Zhu Xi’s comment on seashells was frequently quoted in Chŏsun literati’s essays. In these writings, however, emphasizing on the specific oddity of sea organism found in mountain vanished. Instead, the comment on seashells was referred to more broad and vague oddities, for example, various kinds of oddly-shaped stones found in nature. Some used Zhu Xi’s comment to argue that those odd stones existed even before the dawn of the universe. Notions of the existence of things from the former universe didn't allow any further possible explanation for the formation of them. Chang Hyŏn-gwang(張顯光, 1554-1637), in his essay 'On the Universe', criticized the irrational belief of existence of things from the past universe and suggested his own explanation for the formation of seashells on mountain. Chang apparently criticized Zhu Xi's comment, at the same time he elaborated the cosmological principles in exact same way of Zhu Xi’s.