pycnium

例句：

1. 1.The pycnium was found in the riverbed.
   铅矿在河床上被发现。
2. 2.Lead is a toxic element that can cause serious health problems.
   铅是一种有毒元素，可能导致严重的健康问题。
3. 3.The pycnium was used as an antiquated currency in ancient times.
   铅在古代被用作一种陈旧的货币。