Fossils are incredible clues from the past, preserving evidence of organisms that lived millions of years ago. Here are the major types and how they form:
🪨 Mineralization (Petrification)
This happens when an organism is buried and minerals from groundwater slowly replace its original material. Over time, the remains harden into a rock-like fossil.
👉 A classic example is petrified wood, where even tiny details of the tree are preserved in stone.
🖤 Carbonization
In this process, heat and pressure squeeze out most of an organism’s materials, leaving behind a thin carbon film.
👉 This film outlines the organism, like a shadow frozen in rock.
🐾 Molds, Casts, and Trace Fossils
Molds are hollow impressions left in sediment after an organism decays.
Casts form when those molds fill with minerals, creating a replica of the organism.
Trace fossils capture activity rather than the organism itself—like footprints, trails, or burrows.
🌍 Big Idea:
Fossils don’t just show what organisms looked like—they reveal how they lived, moved, and interacted with their environment.
