化石

1. Origins, structure, and basic meaning

• Structure: 化石 is read as かせき and means a fossil, the preserved body or trace of an organism from the distant past.
• Basic usage: Use 魚の化石 for a fish fossil and 葉の化石 for a leaf fossil, placing the organism before the noun.

2. Common pitfalls and similar expressions

• Difference between 化石 and 遺跡
  • The former is a naturally preserved organism or trace, whereas the latter is a site containing structures or objects left by human activity.