Once you have completed all of your tasks, a red crystal will appear on your planet. Grabbing it will start the apocalypse. To survive through it, you simply need at least 2 creatures to live. The apocalypse is 5 minutes of many more deadly creatures and extra meteors. Don't worry about the flowers, as your creatures can defend against them. If a dinosaur gets a creature you can save it in mid-air by grabbing it. As long as there are 2 creatures left after 5 minutes, then you have survived the apocalypse and gotten the trophy.