How Does Contour Extraction Work?

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I've been modifying squares.py to be able to detect contours of 3D objects. My goal is for it to extract the shapes of 3D objects (i.e. get the squares of a cube). However, whenever I run my code on the image below, drawing the contours gives me a hexagon and a green Y. Is there any way to modify this so that for each contour, I get the polygon of a square/ shape? Thanks!

#!/usr/bin/env python                                 

'''                                                          
Usage:                                                
  ObjectDescriptors.py [<image source>]

  Converts visual objects into basic shapes.
'''

import cv2                                            
import numpy as np                                    

# relative module
import video                                          

# built-in module                                     
import sys

#from bulbs.neo4jserver import Graph
def findShapes(img):
    img = cv2.GaussianBlur(img, (1, 1), 0)
    cv2.imshow("test", img)
    shapeList = []

    gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
    gray = cv2.bilateralFilter(gray, 11, 17, 17)
    edged = cv2.Canny(gray, 0, 200)
    cv2.imshow("test", edged)
    contours, hierarchy = cv2.findContours(edged, cv2.RETR_LIST, cv2.CHAIN_APPROX_SIMPLE)
    for cnt in contours:
        cnt_len = cv2.arcLength(cnt, True)
        cnt = cv2.approxPolyDP(cnt, 0.01*cnt_len, True)
        shapeList.append(cnt)
    keyVertices = []
    for i in shapeList:
        print("Shape Coordinates:",  [pts for pts in i])
    return shapeList def removeDuplicates(contours):
    print(2)    

if __name__ == '__main__':
    from glob import glob
    for fn in glob('../data/perfectcube/png'):
        img = cv2.imread(fn)
        squares = findShapes(img)
        cv2.drawContours( img, squares, 0, (0, 255, 0), 3 )
        cv2.drawContours( img, squares, 1, (255, 0, 0), 3 )
        cv2.drawContours( img, squares, 2, (0, 0, 255), 3 )
        cv2.imshow('squares', img)
        ch = 0xFF & cv2.waitKey()
        if ch == 27:
            break
    cv2.destroyAllWindows()