translation.en: I once asked the mathematicians why it was that mathematicians thought this structure was impossible when sea slugs have been doing it since the Silurian age.
translation.zh: 我曾问过数学家它为什么会这样， 而数学家们认为这种结构是不可能的， 即使海蛞蝓从志留纪开始就一直是这样。