Wǒmen zài tuìcháo hòu de shātān shàng jiǎn dào le jǐ zhī shāqián.
We picked up several sand dollars on the beach after the tide went out.
Tips
memory
Calque of English 'sand dollar' - the dried white skeleton is round and flat like an old silver coin, with a five-petal pattern on top. (In Classical Chinese 沙钱 can also mean a poor-quality copper coin - context disambiguates.)
