Subject: A comb as common ancestor for bilateralia and radiata?

Looking at ediacaran organism's staggered symmetry, a thought arose in me, then 
an intuition. Looking at staggered symmetry arrangements, you can make a comb 
like structure with a spine by alternating each segment between a spine segment 
and a tooth segment. This comb like structure can be rolled up, radially, into 
wheel where the teeth radiate outward and the spine segments combine together in 
the center as a hub, or the spine segments can serve as pivots that grow a tooth 
on one side, and then an inverted pivot that grows a tooth on the other, 
creating a bilaterally symmetric structure. I've drawn a picture here: 
http://imageshack.us/photo/my-images/507/symmetry.png/ . How good is this 
intuition, and what are the problems with it?

Re: A comb as common ancestor for bilateralia and radiata?