A turtle, of course, provides its
own shelter. Eggs are protected by the shelter of the shell. So when turtles-to-be
are inside egg shells inside their mother, they are like houses (turtles-to-be)
inside of houses (eggs) inside of a house (mother turtle), which is where
the title of this riddle-like poem comes from. Of course, Amazon River turtles
spend most of their time in the water, so the house becomes a houseboat.