There are several other vestigial structures like the plica semilunaris in the human body.

人体中还有其它的退化结构，例如半月形褶皱。

Unlike other vestigial structures, though, the appendix isn't always harmless — it can become dangerously inflamed.

不过，与其他退化结构不同，阑尾并不总是无害的，它会严重发炎。