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

On top of this mess, some sand was deposited, buried, lithified into rock, and brought back up to the surface yet again.

在这堆岩层的上面，一些沙子沉积、掩埋、固化成岩，然后又被带回到表面上。

youdao

Sometimes, we will play games on the beach or make some sand sculptures.

有时候，我们会在沙滩上玩一些游戏或者做一些沙雕。

youdao

For example,some plants grow taller and their roots grow deeper into the sand.

VOA: special.2010.01.04

"It throws some sand into the gears, " said Robert Albertson, chief strategist at Sandler O'Neill in New York.

BBC: Obama outlines $117bn bank levy

The sultans would've loved Tom Perkins and he would've felt right at home with them, at least until he decided to kick some sand in their faces when they didn't appreciate his sense of humor.

NEWSWEEK: Business

Two days earlier, it had scooped some sand from a drift, sieved it to a fineness of less than a hundred and fifty microns, and dropped a portion half the size of a baby aspirin into a funnel on its back.

NEWYORKER: The Martian Chroniclers