貝

1. Origins, structure, and basic meaning

• Structure: 貝 is read as かい and is a noun for a shell-bearing mollusk or for its shell.
• Basic usage: Picking up a shell appears in 貝を拾う, while a living shellfish moving appears in 貝が動く.

2. Common pitfalls and similar expressions

• Animal and shell
  • Depending on context, it can identify the living animal or the shell left by it.
• Difference from 貝殻
  • The comparison term specifically identifies the hard shell, while this word can also denote the animal itself.