How Do Soft Things Fossilize?
Goals:

• Understand why soft-bodied organisms rarely fossilize.
• Learn about exceptional fossilization conditions.
• Explore how soft-bodied fossils are preserved as impressions or mineralized films.
• Create their own “fossils” to simulate the process.

Vocabulary

• Soft-bodied – An organism without bones or hard shells.
• Fossil – The preserved remains or trace of an ancient organism.
• Impression fossil – A mark or shape left in sediment by a body.
• Mineralization – The process of minerals replacing or coating organic material.
• Decay – The natural breakdown of dead organisms.

Read-Aloud Lesson
Most of the animals that lived in the Ediacaran oceans were soft—no bones, no shells, just squishy bodies like jellyfish or worms. That makes them hard to find today.When something dies, it usually decays quickly. Soft parts rot or are eaten. But sometimes, if a soft creature is buried quickly in mud or fine sediment, and there isn’t much oxygen, it can leave behind a fossil.These fossils don’t look like bones. They look more like shadows—a ripple, a squish, or a gentle imprint. Sometimes, the body itself is replaced by minerals that preserve its shape.That’s how we know about creatures like Dickinsonia or Haootia—not from bones, but from the shapes they left behind in ancient sea floors.

Activity: Make a Soft-Body Fossil Simulation

Materials:

• Air-dry clay or modeling dough
• Small soft items (gummy worms, soft toy jellyfish, leaf pieces, etc.)
• Plaster of Paris or salt dough
• Shallow trays or paper plates

Instructions:

• Press clay into a tray to represent the sea floor.
• Gently press soft objects into the clay to make impressions (do not leave them in).
• Carefully remove the object—observe the impression.
• (Optional) Pour a thin layer of plaster of Paris over the impression to “preserve” it.
• Once dry, flip and reveal your “fossil.”

Discussion Questions:

• What parts made the clearest impressions?
• What might happen if the object wasn’t buried quickly?
• Why are soft body fossils so rare?

Wrap-Up

• Revisit: "What needs to happen for a soft body to fossilize?"
• Emphasize: Fossilization of soft things is rare, and that’s why the few we’ve found are so special.