in chapter three of the grapes of wrath, what is the significance of the turtle

The turtle is a metaphor for the working class farmers whose stories and struggles are recounted in The Grapes of Wrath. The turtle plods along dutifully, but is consistently confronted with danger and setbacks. Significantly, the dangers posed to the turtle are those of modernity and business. It is the intrusion of cars and the building of highways that endanger the turtle. The truck that strikes it is a symbol of big business and commerce. The Joad family that will soon be introduced will experience similar travails as the turtle, as they plod along wishing only to survive, yet are brutally pushed aside by corporate interests.