Across
- 3. very small
- 5. not exact or accurate; estimated
- 6. cause to pass from one place to another
- 9. a split in the surface of something
- 13. a unit apart or by itself; cause to be apart
- 15. to eject material like a volcano
- 17. required; not voluntary
- 18. a thin barrier
- 19. animals that begin life in the water before growing into a terrestrial adult
- 20. a nerve cell
Down
- 1. of great value
- 2. designed for people to live in
- 4. a person who offers to do a task
- 7. the bones that make up a backbone
- 8. to get smaller or more compact
- 10. able to adjust to new conditions
- 11. so small it can only be seen with a microscope
- 12. be full of or swarming with
- 14. of, on, or relating to Earth
- 16. a scent used by animals to communicate
- 21. able to be used for a practical purpose
- 22. the central part of something