It's full of tannic acid which in part gives it its red colour but also helps it resist fires.

树皮中富含单宁酸，这在一定程度上使它呈现红色，但也有助于帮其抵御火灾。

It takes years for a skeleton to vanish, but the shoes treated with tannic acid—they won't eat them.

骸骨需要几年才能消失，但是用鞣酸处理过的鞋子——海水无法吞噬它们。