The first thing I know about the tortoises is they will outlive all of their owner. The good part is you can write on their back your family tree and history, and this will be carried on to a few generations to come in your family.
The next thing I can think of is your great-great-great-great-great grandsons will know from reading the turtle's back alone that they had an ancestor named @dcxg who got behavioral issues in that society.