The eggs of the immortal shrimp can lie dormant for many years (Millennium is exaggerated), and will revive when there is enough water. Then quickly hatch, grow and lay eggs. If the environment is right, new eggs will hatch and start a new cycle. If it doesn't fit, it will sleep like its parents. Fairy shrimp has lived for 200 million years from generation to generation, and it is still multiplying. Not a fairy shrimp can live for 100 million years.