sea gravel

例句：

1. 1.The beach was littered with sea gravel and shells.
   海滩上到处都是海砂和贝壳。
2. 2.The old ship was buried in the sea gravel.
   旧船被埋在海砂中。
3. 3.The builders used sea gravel to level the land.
   建筑者用海砂来平整土地。