When God had finished making all the different animals he invited them to a big party to celebrate. Every single animal brushed its fur and went, looking neat and tidy, except the tortoises. It was very rude not to send a note explaining why they couldn't come to the party, so next day God called down to the tortoises opened their sleepy eyes, "It was so nice and warm at home that we stayed there," they said, and went back to sleep. "In that case you can carry your on your homes around on your backs," said God. And that is why all tortoises live inside a thick shell.