If you want a mystery, figure out where turtles came from. There are several decent explainations for the arrangement of the tree or as Gould and others call it, the bush. Its a matter of gathering more evidence to finalize the details. But, in the case of the turtle, no reasonable explaination has been brought forth yet.
Turtles appear today much as they appeared hundreds of millions of years ago.
Figire it out and win the Nobel Prize.