她在沙滩上发现了一个漂亮的贝壳，这种贝壳曾经被用作货币。

She found a beautiful ___cowry on the beach, which was once used as currency.

她在沙滩上捡到了一个漂亮的贝壳，原来是一种叫宝贝螺的海螺。

She picked up a beautiful shell on the beach, which turned out to be a ___cowry.