The Boustrophedon is a lumbering Tarrasque-like beast that is part organic, and part machine. Like its namesake it boustrophedonically travels the Vast Deferens, consuming everything in its path for fuel. Consequently, in its wake there is the opportunity for new life to emerge from the tilled and enriched rubble.
The Boustrophedon is essentially the reason why it is impossible to settle in the Vast Deferens, because although it is slow, its path tills the entirety of the Vast Deferens indiscriminately. It was built as a tool to ensure that the ecosystem of the Vast Deferens did not ever grow stagnant.