&#62; If you start with two disconnected cell groups, how do you know when they collide?<p>You create 'dead' cells in between that connect the two populations.<p>That's also why you can't remove them. Remember, this is a simulation of a fabric, the dead cells not being there all the time is an optimization, in a real fabric all cells would exist all the time.<p>The async component is the fact that there is no global authority supplying a clock, each 'peer' is on its own from the moment of power-up.