Across
- 2. A large, swimming predator from the Cambrian seas.
- 4. The process by which plants and some microbes make food from sunlight.
- 9. Rocky objects orbiting the Sun, mostly between Mars and Jupiter.
- 10. The movement of the plates on Earth’s crust.
- 13. Cells with a nucleus and complex structures.
- 15. Preserved remains or signs of ancient organisms.
- 17. A rapid burst of diverse life forms about 540 million years ago.
- 18. A gas vital for most life on Earth.
- 20. A prehistoric fish with armored plates covering its head and body.
- 23. Moon: Earth's natural satellite, formed after the Theia impact.
- 24. A time when Earth was covered in ice.
- 25. A spiky, worm-like Cambrian animal with legs and back spines.
- 26. The rapid expansion that began the universe.
- 28. Soft-bodied sea animals with tentacles that often sting.
Down
- 1. The essential liquid made of H₂O that supports life.
- 3. Ancient microbes that produced oxygen via photosynthesis.
- 5. The layer of gases surrounding Earth.
- 6. An opening where magma erupts from within Earth.
- 7. The third planet from the Sun, where life exists.
- 8. An extinct armored arthropod with a segmented body.
- 11. A Mars-sized body that likely collided with early Earth.
- 12. A stream of charged particles flowing from the Sun.
- 14. A five-eyed creature with a flexible snout used to grab food.
- 16. A structure built by tiny coral animals
- 19. A long nose with a mouth at the end. Opabinia has one.
- 21. The galaxy that holds our solar system.
- 22. An invisible shield around Earth that deflects solar wind.
- 27. A basic force of our universe; it pulls objects toward each other.