Difference between 貝 and 貝殻


I would like to know if there's any difference between 貝 and 貝殻, and if these
words are interchangeable.




貝 has several meanings but usually it refers to the shellfish as an animal.  
貝殻 means only the shell.

かい【貝】貝殻をもつ軟体動物。ハマグリなどの二枚貝、サザエなどの巻き貝、ツノガイなどの掘足類を主にいう。  
[https://dictionary.goo.ne.jp/jn/35183/meaning/m1u/貝/](https://dictionary.goo.ne.jp/jn/35183/meaning/m1u/%E8%B2%9D/)

かいがら【貝殻】貝の軟体を外側から包む石灰質などからなる硬い物質。  
[https://dictionary.goo.ne.jp/jn/35485/meaning/m1u/貝殻/](https://dictionary.goo.ne.jp/jn/35485/meaning/m1u/%E8%B2%9D%E6%AE%BB/)

