かせき化石kaseki
1.

A natural remnant of ancient plants or animals that has been preserved in sedimentary rock, often showcasing the structure or features of the original organism.

2.

An object, tradition, or mentality that is considered outdated or relic-like, typically used to describe someone who struggles to adapt to contemporary ways of thinking or living.

3.

The process by which organic material undergoes transformation into a stone-like substance through mineralization or other geological processes.

Example:

私が手にしてるのは貝の化石です。

かせきねんりょう化石燃料kasekinenryou
1.

A type of energy source formed from the remains of ancient plants and animals that have been subjected to heat and pressure over geological time, resulting in substances like coal, oil, and natural gas.

2.

Organic materials transformed under specific geological conditions, which store energy that can be released through combustion for use in various applications, including electricity generation and transportation fuels.

3.

Energy resources derived from the decomposition and alteration of biological matter over millions of years, primarily used as a major source of energy in industrialized societies.

Example:

その大陸は化石燃料が豊富だ。

iきたkitaかせき化石kaseki
1.

A species that has remained relatively unchanged over long geological periods, serving as a representative of ancient life forms.

2.

An organism that possesses characteristics similar to its prehistoric relatives, often providing insight into evolutionary history.

3.

A term used to describe a species that has survived major extinction events and continues to exist in a form that resembles its ancestors.