Simply put some sand in the bottom of the jar (colored play sand works great for this) and add the seashells.

只要将沙子铺到瓶底，(如果是彩沙就更漂亮了)然后再放入贝壳。

youdao

The oil floats on top of the jar and seals out air, leaving water to collect at the bottom, where it ACTS like a Petri dish for botulism.

油浮到罐头的顶部，封住空气，留下水在底部聚集，就像是为肉毒菌提供一个有盖培养皿。

youdao

They had an old birds cage, and it had a jar at the bottom.

他们有一个旧的鸟笼子，笼子底部有一个瓶子。

youdao

The butterfly would flutter for a few moments, sink to the bottom of the jar, and slowly expire.

NPR: Excerpt: 'At Large and At Small'

At the bottom of the killing jar was a piece of cotton saturated with carbon tetrachloride.

NPR: Excerpt: 'At Large and At Small'

There ought to be at least a nickel's width of clearance between the whirring blades and the bottom or sides of the blender jar.

WSJ: How to Ace a Google Interview