Magnetometers can be used for navigation purposes, however. Jason uses a magnetometer as a compass to determine which way is north. That is a very good question. Well, it's the same for underwater sea animals. In fact, they recently found something called archebacteria which is neither plant or animal.
Rock changes as it ages.
We are studying how the rock changes with time in the first few years after it's created. If you want to send us a question, head over to the question page .