They are covered with a thick, black substance.

VOA: special.2010.04.07

They realized that the rice could fill up the entire world with a thick layer.

他们发现米粒,能厚厚地覆盖全世界。

哈佛公开课 - 幸福课课程节选

They realized that the rice could fill up the entire world with a thick layer.

他们发现米粒,能厚厚地覆盖全世界。

哈佛公开课 - 幸福课课程节选